Ang granite ay isang uri ng igneous rock na kinukuha dahil sa matinding lakas, densidad, tibay, at resistensya nito sa kalawang. Ngunit ang granite ay maraming gamit din – hindi lamang ito para sa mga parisukat at parihaba! Sa katunayan, may kumpiyansa kaming nakikipagtulungan sa mga bahagi ng granite na ginawa sa mga hugis, anggulo, at kurba ng lahat ng uri nang regular—na may mahusay na mga resulta.
Through our state of the art processing, cut surfaces can be exceptionally flat. These qualities make granite the ideal material to create custom-size and custom-design machine bases and metrology components. Granite is:
■ maaaring makinahin
■ eksaktong patag kapag pinutol at tinapos
■ lumalaban sa kalawang
■ matibay
■ pangmatagalan
Madali ring linisin ang mga bahagi ng granite. Kapag gumagawa ng mga pasadyang disenyo, siguraduhing pumili ng granite dahil sa mga nakahihigit na benepisyo nito.

MGA PAMANTAYAN / MGA APLIKASYON SA MATAAS NA PAGKASUOT
Ang granite na ginagamit ng ZHHIMG para sa aming mga karaniwang produkto ng surface plate ay may mataas na nilalaman ng quartz, na nagbibigay ng mas mataas na resistensya sa pagkasira at pagkasira. Ang aming mga Superior Black na kulay ay may mababang water absorption rates, na nagpapaliit sa posibilidad na kalawangin ang iyong mga precision gauge habang nakalagay sa mga plato. Ang mga kulay ng granite na inaalok ng ZHHIMG ay nagreresulta sa mas kaunting silaw, na nangangahulugang mas kaunting pagkapagod ng mata para sa mga indibidwal na gumagamit ng mga plato. Pinili namin ang aming mga uri ng granite habang isinasaalang-alang ang thermal expansion sa pagsisikap na mapanatiling minimal ang aspetong ito.

CUSTOM APPLICATIONS
Kapag ang iyong aplikasyon ay nangangailangan ng isang plato na may mga pasadyang hugis, may sinulid na insert, mga puwang o iba pang machining, gugustuhin mong pumili ng materyal tulad ng Black Jinan Black. Ang natural na materyal na ito ay nag-aalok ng superior na stiffness, mahusay na vibration dampening, at pinahusay na machinability.

Mahalagang tandaan na ang kulay lamang ay hindi indikasyon ng pisikal na katangian ng bato. Sa pangkalahatan, ang kulay ng granite ay direktang nauugnay sa presensya o kawalan ng mga mineral, na maaaring walang epekto sa mga katangiang bumubuo sa mahusay na materyal para sa surface plate. May mga granite na kulay rosas, kulay abo, at itim na mahusay para sa mga surface plate, pati na rin ang mga granite na kulay itim, kulay abo, at kulay rosas na hindi angkop para sa mga aplikasyon na may katumpakan. Ang mga kritikal na katangian ng granite, na may kaugnayan sa paggamit nito bilang materyal para sa surface plate, ay walang kinalaman sa kulay, at ang mga sumusunod:
■ Katatagan (paglihis sa ilalim ng bigat - ipinapahiwatig ng Modulus ng Elastisidad)
■ Katigasan
■ Densidad
■ Paglaban sa pagkasira
■ Katatagan
■ Porosidad

Sinubukan na namin ang maraming materyales ng granite at pinagkumpara ang mga materyales na ito. Sa wakas, nakuha namin ang resulta, ang Jinan black granite ang pinakamahusay na materyal na aming nakilala. Ang Indian Black granite at South African granite ay katulad ng Jinan Black Granite, ngunit ang kanilang mga pisikal na katangian ay mas mababa kaysa sa Jinan Black Granite. Patuloy na maghahanap ang ZHHIMG ng mas maraming materyales ng granite sa mundo at pagkukumparahin ang kanilang mga pisikal na katangian.

Para sa karagdagang impormasyon tungkol sa granite na angkop para sa iyong proyekto, mangyaring makipag-ugnayan sa amin.info@zhhimg.com.

Iba't ibang pamantayan ang ginagamit ng iba't ibang tagagawa. Maraming pamantayan sa mundo.
DIN Standard, ASME B89.3.7-2013 o Federal Specification GGG-P-463c (Granite Surface Plates) at iba pa bilang batayan para sa kanilang mga ispesipikasyon.

At maaari kaming gumawa ng granite precision inspection plate ayon sa iyong mga pangangailangan. Malugod kaming tinatanggap na makipag-ugnayan sa amin kung nais mong malaman ang higit pang impormasyon tungkol sa iba pang mga pamantayan.

Ang pagiging patag ay maaaring ituring bilang lahat ng mga punto sa ibabaw na nakapaloob sa loob ng dalawang parallel na patag, ang base plane at ang roof plane. Ang pagsukat ng distansya sa pagitan ng mga patag ay ang kabuuang patag ng ibabaw. Ang pagsukat ng pagiging patag na ito ay karaniwang may tolerance at maaaring kabilang ang isang grade designation.

Halimbawa, ang mga tolerance sa flatness para sa tatlong karaniwang grado ay tinukoy sa pederal na ispesipikasyon gaya ng tinutukoy ng sumusunod na pormula:
■ Grado sa Laboratoryo AA = (40 + dayagonal na parisukat/25) x .000001" (unilateral)
■ Baitang ng Inspeksyon A = Baitang ng Laboratoryo AA x 2
■ Baitang B sa Silid ng Kagamitan = Baitang AA sa Laboratoryo x 4.

Para sa mga karaniwang laki ng mga surface plate, ginagarantiya namin ang mga flatness tolerance na lumalagpas sa mga kinakailangan ng ispesipikasyong ito. Bukod sa flatness, tinutugunan din ng ASME B89.3.7-2013 at Federal Specification GGG-P-463c ang mga paksang kabilang ang: katumpakan ng paulit-ulit na pagsukat, mga katangian ng materyal ng mga granite ng surface plate, surface finish, lokasyon ng support point, stiffness, mga katanggap-tanggap na paraan ng inspeksyon, pag-install ng mga threaded insert, atbp.

Ang mga granite surface plate at granite inspection plate ng ZHHIMG ay nakakatugon o lumalagpas sa lahat ng mga kinakailangang nakasaad sa ispesipikasyong ito. Sa kasalukuyan, walang tiyak na ispesipikasyon para sa mga granite angle plate, parallel, o master square.

At makikita mo ang mga pormula para sa iba pang mga pamantayan saI-DOWNLOAD.

Una, mahalagang panatilihing malinis ang plato. Ang alikabok na dala ng hangin ay kadalasang siyang pinakamalaking pinagmumulan ng pagkasira at pagkasira ng isang plato, dahil may posibilidad itong tumagos sa mga piraso ng trabaho at sa mga ibabaw na may kontak ng mga gauge. Pangalawa, takpan ang iyong plato upang protektahan ito mula sa alikabok at pinsala. Ang buhay ng pagkasira ay maaaring pahabain sa pamamagitan ng pagtakip sa plato kapag hindi ginagamit, sa pamamagitan ng paminsan-minsang pag-ikot ng plato upang ang isang bahagi ay hindi labis na magamit, at sa pamamagitan ng pagpapalit ng mga steel contact pad sa gauging ng mga carbide pad. Gayundin, iwasan ang paglalagay ng pagkain o soft drink sa plato. Tandaan na maraming soft drink ang naglalaman ng carbonic o phosphoric acid, na maaaring magtunaw ng mas malambot na mineral at mag-iwan ng maliliit na butas sa ibabaw.

Depende ito sa kung paano ginagamit ang plato. Kung maaari, inirerekomenda namin ang paglilinis ng plato sa simula ng araw (o shift ng trabaho) at muli sa pagtatapos. Kung ang plato ay marumihan, lalo na sa mga mamantika o malagkit na likido, dapat itong linisin kaagad.

Linisin ang plato nang regular gamit ang likido o ZHHIMG Waterless surface plate cleaner. Mahalaga ang pagpili ng mga solusyon sa paglilinis. Kung gagamit ng volatile solvent (acetone, lacquer thinner, alcohol, atbp.), ang pagsingaw ay magpapalamig sa ibabaw, at magpapabaluktot dito. Sa kasong ito, kinakailangang hayaang maging normal ang plato bago gamitin dahil kung hindi ay magkakaroon ng mga pagkakamali sa pagsukat.

Ang tagal ng oras na kinakailangan para maging normal ang plato ay mag-iiba depende sa laki ng plato, at sa tagal ng pagpapalamig. Ang isang oras ay dapat sapat para sa mas maliliit na plato. Maaaring kailanganin ang dalawang oras para sa mas malalaking plato. Kung gagamit ng water-based cleaner, magkakaroon din ng kaunting evaporative chilling.

Pananatilihin din ng plato ang tubig, at maaari itong magdulot ng kalawang sa mga bahaging metal na nakadikit sa ibabaw. Ang ilang panlinis ay nag-iiwan din ng malagkit na residue pagkatapos matuyo, na siyang aakit ng alikabok na papalipad sa hangin, at sa katunayan ay magpapataas ng pagkasira, sa halip na bawasan ito.

Depende ito sa paggamit ng plato at sa kapaligiran. Inirerekomenda namin na ang isang bagong plato o precision granite accessory ay sumailalim sa isang buong recalibration sa loob ng isang taon mula sa pagbili. Kung ang granite surface plate ay madalas gamitin, maaaring ipinapayong paikliin ang agwat na ito sa anim na buwan. Ang buwanang inspeksyon para sa paulit-ulit na mga error sa pagsukat gamit ang Electronic level, o katulad na aparato ay magpapakita ng anumang mga umuusbong na marka ng pagkasira at aabutin lamang ng ilang minuto upang maisagawa. Matapos matukoy ang mga resulta ng unang recalibration, ang agwat ng calibration ay maaaring pahabain o paikliin kung pinahihintulutan o kinakailangan ng iyong internal quality system.

Maaari kaming mag-alok ng serbisyo upang matulungan kang siyasatin at i-calibrate ang iyong granite surface plate.

Mayroong ilang mga posibleng dahilan para sa mga pagkakaiba-iba sa pagitan ng mga kalibrasyon:

• Ang ibabaw ay hinugasan gamit ang mainit o malamig na solusyon bago ang pagkakalibrate, at hindi binigyan ng sapat na oras upang maging normal.
• Hindi maayos ang suporta ng plato
• Pagbabago ng temperatura
• Mga draft
• Direktang sikat ng araw o iba pang init na nagmumula sa ibabaw ng plato. Siguraduhing hindi pinapainit ng ilaw sa itaas ang ibabaw.
• Mga pagkakaiba-iba sa patayong gradient ng temperatura sa pagitan ng taglamig at tag-araw (Kung maaari, alamin ang patayong gradient na temperatura sa oras na isinasagawa ang kalibrasyon.)
• Hindi binigyan ng sapat na oras ang plato para maging normal pagkatapos ng pagpapadala
• Maling paggamit ng kagamitan sa inspeksyon o paggamit ng kagamitang hindi naka-calibrate
• Pagbabago sa ibabaw na resulta ng pagkasira

Ilang uri ng butas ang nasa precision granite?

Mga Puwang sa mga Bahagi ng Precision Granite

Para sa maraming pabrika, silid ng inspeksyon, at laboratoryo, ang mga precision granite surface plate ang siyang basehan para sa tumpak na pagsukat. Dahil ang bawat linear na pagsukat ay nakadepende sa isang tumpak na reference surface kung saan kinukuha ang mga huling sukat, ang mga surface plate ang nagbibigay ng pinakamahusay na reference plane para sa inspeksyon at layout bago ang machining. Ang mga ito rin ay mainam na base para sa paggawa ng mga sukat ng taas at pag-gage ng mga ibabaw. Bukod pa rito, ang mataas na antas ng pagiging patag, katatagan, pangkalahatang kalidad, at pagkakagawa ay ginagawa silang isang mahusay na pagpipilian para sa pag-mount ng mga sopistikadong mekanikal, elektroniko, at optical gaging system. Para sa alinman sa mga prosesong ito ng pagsukat, mahalagang panatilihing naka-calibrate ang mga surface plate.

Repeat Measurements and Flatness

Ang parehong patag at paulit-ulit na pagsukat ay mahalaga upang matiyak ang isang katumpakan ng ibabaw. Ang patag ay maaaring ituring bilang lahat ng mga punto sa ibabaw na nakapaloob sa loob ng dalawang parallel na eroplano, ang base plane at ang roof plane. Ang pagsukat ng distansya sa pagitan ng mga eroplano ay ang pangkalahatang patag ng ibabaw. Ang pagsukat ng patag na ito ay karaniwang may tolerance at maaaring kabilang ang isang grade designation.

The flatness tolerances for three standard grades are defined in the federal specification as determined by the following formula:

DIN Standard, GB Standard, ASME Standard, JJS standard... iba't ibang bansa na may iba't ibang paninindigan...

Higit pang detalye tungkol sa pamantayan.

In addition to flatness, repeatability must be ensured. A repeat measurement is a measurement of local flatness areas. It is a measurement taken anywhere on the surface of a plate that will repeat within the stated tolerance. Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.

Upang matiyak na ang isang surface plate ay nakakatugon sa parehong mga ispesipikasyon ng flatness at repeat measurement, dapat gamitin ng mga tagagawa ng granite surface plates ang Federal Specification GGG-P-463c bilang batayan para sa kanilang mga ispesipikasyon. Tinutugunan ng pamantayang ito ang katumpakan ng repeat measurement, mga katangian ng materyal ng surface plate granite, surface finish, lokasyon ng support point, stiffness, mga katanggap-tanggap na pamamaraan ng inspeksyon at pag-install ng mga threaded insert.

Checking Plate Accuracy

Sa pamamagitan ng pagsunod sa ilang simpleng alituntunin, ang isang pamumuhunan sa isang granite surface plate ay dapat tumagal nang maraming taon. Depende sa paggamit ng plate, kapaligiran sa pagawaan, at kinakailangang katumpakan, ang dalas ng pagsusuri sa katumpakan ng surface plate ay nag-iiba. Ang isang pangkalahatang tuntunin ay ang isang bagong plate ay makatanggap ng buong muling pagkakalibrate sa loob ng isang taon mula sa pagbili. Kung ang plate ay madalas na ginagamit, ipinapayong paikliin ang agwat na ito sa anim na buwan.

Before a surface plate has worn beyond specification for overall flatness, it will show worn or wavy posts. Monthly inspection for repeat measurement errors using a repeat reading gage will identify wear spots. A repeat reading gage is a high-precision instrument that detects local error and can be displayed on a high magnification electronic amplifier.

An effective inspection program should include regular checks with an autocollimator, providing actual calibration of overall flatness traceable to National Institute of Standards and Technology (NIST). Comprehensive calibration by the manufacturer or an independent company is necessary from time to time.

Variations Between Calibrations

Sa ilang mga kaso, may mga pagkakaiba-iba sa pagitan ng mga pagkakalibrate ng surface plate. Minsan, ang mga salik tulad ng pagbabago sa surface na resulta ng pagkasira, maling paggamit ng kagamitan sa inspeksyon o paggamit ng kagamitang hindi naka-calibrate ay maaaring magpaliwanag sa mga pagkakaiba-ibang ito. Gayunpaman, ang dalawang pinakakaraniwang salik ay ang temperatura at suporta.

One of the most important variables is temperature. For instance, the surface might have been washed with a hot or cold solution prior to calibration and not allowed sufficient time to normalize. Other causes of temperature change include drafts of cold or hot air, direct sunlight, overhead lighting or other sources of radiant heat on the surface of the plate.

There also can be variations in the vertical temperature gradient between winter and summer. In some cases, the plate is not allowed sufficient time to normalize after shipment. It is a good idea to record the vertical gradient temperature at the time the calibration is performed.

Another common cause for calibration variation is a plate that is improperly supported. A surface plate should be supported at three points, ideally located 20% of the length in from the ends of the plate. Two supports should be located 20% of the width in from the long sides, and the remaining support should be centered.

Only three points can rest solidly on anything but a precision surface. Attempting to support the plate at more than three points will cause the plate to receive its support from various combinations of three points, which will not be the same three points on which it was supported during production. This will introduce errors as the plate deflects to conform to the new support arrangement. Consider using steel stands with support beams designed to line up with the proper support points. Stands for this purpose are generally available from the surface plate manufacturer.

If the plate is properly supported, precise leveling is only necessary if an application specifies it. Leveling is not necessary to maintain the accuracy of a properly supported plate.

Extend Plate Life

Ang pagsunod sa ilang mga alituntunin ay makakabawas sa pagkasira ng isang granite surface plate at sa huli, magpapahaba sa buhay nito.

Una, mahalagang panatilihing malinis ang plato. Ang alikabok na dala ng hangin ay kadalasang siyang pinakamalaking pinagmumulan ng pagkasira at pagkasira ng isang plato, dahil may posibilidad itong maipit sa mga workpiece at sa mga ibabaw na nakadikit sa mga gauge.

It also is important to cover plates to protect it from dust and damage. Wear life can be extended by covering the plate when not in use.

Paikutin ang plato paminsan-minsan upang hindi labis na magamit ang isang bahagi. Inirerekomenda rin na palitan ang mga steel contact pad sa gauging ng mga carbide pad.

Avoid setting food or soft drinks on the plate. Many soft drinks contain either carbonic or phosphoric acid, which can dissolve the softer minerals and leave small pits in the surface.

Where to Relap

Kapag kailangang i-resurface ang isang granite surface plate, isaalang-alang kung ipapagawa ang serbisyong ito on-site o sa calibration facility. Mas mainam na ipa-relapse ang plate sa pabrika o sa isang nakalaang pasilidad. Gayunpaman, kung ang plate ay hindi masyadong malubha ang pagkasira, kadalasan ay nasa loob ng 0.001 pulgada ng kinakailangang tolerance, maaari itong i-resurface on-site. Kung ang isang plate ay nasira hanggang sa puntong ito ay higit sa 0.001 pulgada ang layo mula sa tolerance, o kung ito ay may malalang butas o butas, dapat itong ipadala sa pabrika para sa paggiling bago i-relapse.

A calibration facility has the equipment and factory setting providing the optimum conditions for proper plate calibration and rework if necessary.

Dapat maging maingat sa pagpili ng on-site calibration at resurfacing technician. Humingi ng akreditasyon at beripikahin kung ang kagamitang gagamitin ng technician ay may traceable calibration. Mahalaga rin ang karanasan, dahil maraming taon ang kailangan para matutunan kung paano gamitin nang tama ang precision granite.

Critical measurements start with a precision granite surface plate as a baseline. By ensuring a reliable reference by using a properly calibrated surface plate, manufacturers have one of the essential tools for reliable measurements and better quality parts.Q

Checklist for Calibration Variations

1. Ang ibabaw ay hinugasan gamit ang mainit o malamig na solusyon bago ang pagkakalibrate at hindi binigyan ng sapat na oras upang maging normal.

2. Hindi wastong nasuportahan ang plato.

3. Pagbabago ng temperatura.

4. Mga burador.

5. Direktang sikat ng araw o iba pang radiant heat sa ibabaw ng plato. Siguraduhing hindi pinapainit ng ilaw sa itaas ang ibabaw.

6. Mga pagkakaiba-iba sa patayong gradient ng temperatura sa pagitan ng taglamig at tag-araw. Kung maaari, alamin ang patayong gradient na temperatura sa oras na isinasagawa ang pagkakalibrate.

7. Hindi binigyan ng sapat na oras ang plato para maging normal pagkatapos ng pagpapadala.

8. Maling paggamit ng kagamitan sa pag-iinspeksyon o paggamit ng kagamitang hindi naka-calibrate.

9. Pagbabago sa ibabaw na resulta ng pagkasira.

Tech Tips

• Dahil ang bawat linear na pagsukat ay nakasalalay sa isang tumpak na reference surface kung saan kinukuha ang mga pangwakas na dimensyon, ang mga surface plate ay nagbibigay ng pinakamahusay na reference plane para sa inspeksyon ng trabaho at layout bago ang machining.
• Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.
• Dapat kasama sa isang epektibong programa ng inspeksyon ang mga regular na pagsusuri gamit ang isang autocollimator, na nagbibigay ng aktwal na kalibrasyon ng pangkalahatang kapatagan na maaaring masubaybayan sa National Inspection Authority.

Sa mga partikulo ng mineral na bumubuo sa granite, mahigit 90% ay feldspar at quartz, kung saan ang feldspar ang pinakamarami. Ang feldspar ay kadalasang puti, kulay abo, at pula-balat, at ang quartz ay halos walang kulay o kulay-abong puti, na siyang bumubuo sa pangunahing kulay ng granite. Ang feldspar at quartz ay matigas na mineral, at mahirap itong igalaw gamit ang kutsilyong bakal. Kung tungkol sa mga maitim na batik sa granite, karamihan ay itim na mika, may ilang iba pang mineral. Bagama't medyo malambot ang biotite, hindi mahina ang kakayahan nitong labanan ang stress, at kasabay nito ay mayroon silang maliit na dami sa granite, kadalasang wala pang 10%. Ito ang kondisyon ng materyal kung saan ang granite ay partikular na malakas.

Isa pang dahilan kung bakit matibay ang granite ay dahil ang mga particle ng mineral nito ay mahigpit na nakadikit sa isa't isa at nakabaon sa isa't isa. Ang mga butas ay kadalasang bumubuo ng wala pang 1% ng kabuuang volume ng bato. Nagbibigay ito sa granite ng kakayahang makayanan ang malalakas na presyon at hindi madaling mapasok ng kahalumigmigan.

Ang mga bahagi ng granite ay gawa sa bato na walang kalawang, acid at alkali resistance, mahusay na wear resistance at mahabang buhay ng serbisyo, walang espesyal na maintenance. Ang mga bahagi ng granite precision ay kadalasang ginagamit sa tooling ng industriya ng makinarya. Samakatuwid, ang mga ito ay tinatawag na granite precision components o granite components. Ang mga katangian ng mga bahagi ng granite precision ay halos kapareho ng sa mga granite platform. Panimula sa tooling at pagsukat ng mga bahagi ng granite precision: Ang precision machining at micro machining technology ay mahahalagang direksyon ng pag-unlad ng industriya ng paggawa ng makinarya, at ang mga ito ay naging isang mahalagang tagapagpahiwatig upang masukat ang isang high-tech na antas. Ang pag-unlad ng makabagong teknolohiya at industriya ng depensa ay hindi mapaghihiwalay sa precision machining at micro-machining technology. Ang mga bahagi ng granite ay maaaring maayos na madulas sa pagsukat, nang walang stagnation. Ang pagsukat ng work surface, ang mga pangkalahatang gasgas ay hindi nakakaapekto sa katumpakan ng pagsukat. Ang mga bahagi ng granite ay kailangang idisenyo at gawin ayon sa mga kinakailangan ng demand side.

Patlang ng aplikasyon:

Gaya ng alam nating lahat, parami nang parami ang mga makina at kagamitan na pumipili ng mga precision granite component.

Ang mga bahaging granite ay ginagamit para sa dynamic motion, linear motors, cmm, cnc, laser machine...

maligayang pagdating sa pakikipag-ugnayan sa amin para sa karagdagang impormasyon.

Ang mga aparatong panukat ng granite at mga mekanikal na bahagi ng granite ay gawa sa mataas na kalidad na Jinan Black granite. Dahil sa kanilang mataas na katumpakan, mahabang tagal, mahusay na katatagan at resistensya sa kalawang, ang mga ito ay lalong ginagamit sa inspeksyon ng produkto ng modernong industriya at mga siyentipikong larangan tulad ng mekanikal na aerospace at mga siyentipikong pananaliksik.

Mga Kalamangan

----Dobleng tigas ng bakal na hinulma;

----Ang pinakamaliit na pagbabago sa dimensyon ay dahil sa mga pagbabago sa temperatura;

----Walang pagkaantala, kaya walang pagkaantala sa trabaho;

----Walang mga burr o nakausli dahil sa pinong istruktura ng butil at hindi gaanong pagdikit, na nagsisiguro ng mataas na antas ng pagkapatag sa mahabang buhay ng serbisyo at hindi nagdudulot ng pinsala sa ibang mga bahagi o instrumento;

----Madaling gamitin sa mga materyales na magnetiko nang walang problema;

---- Mahabang buhay at walang kalawang, na nagreresulta sa mababang gastos sa pagpapanatili.

Ang mga precision granite surface plate ay may katumpakan at mataas na pamantayan ng pagkapatas upang makamit ang katumpakan at ginagamit bilang base para sa pag-mount ng mga sopistikadong mekanikal, elektroniko, at optical gauging system.

Ilan sa mga natatanging katangian ng granite surface plate:

Pagkakapareho sa Katigasan;

Tumpak na mga Kondisyon sa ilalim ng karga;

Sumisipsip ng Panginginig;

Madaling Linisin;

Hindi tinatablan ng pambalot;

Mababang Porosidad;

Hindi Nakasasakit;

Hindi Magnetiko

Mga Bentahe ng Granite Surface Plate

First, the rock after a long period of natural aging, uniform structure, coefficient minimum, the internal stress completely disappear, not deformed, so the precision is high.

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Precision Granite Base Can Improve Machine Tool Performances

Requirements are constantly increasing in mechanical engineering in general and in machine tool construction in particular. Achieving maximum precision and performance values without increasing costs are constant challenges to being competitive. The machine tool bed is a decisive factor here. Therefore, more and more machine tool manufacturers are relying on granite. Due to its physical parameters, it offers clear advantages that cannot be achieved with steel or polymer concrete.

Granite is a so-called volcanic deep rock and has a very dense and homogeneous structure with an extremely low coefficient of expansion, low thermal conductivity and high vibration damping.

Below you will discover why the common opinion that granite is mainly only suitable as machine base for high-end coordinate measuring machines is long outdated and why this natural material as a machine tool base is a very advantageous alternative to steel or cast iron even for high-precision machine tools.

We can manufacture granite components for dynamic motion, granite components for linear motors, granite components for ndt, granite components for xray, granite components for cmm, granite components for cnc, granite precision for laser, granite components for aerospace, granite components for precision stages...

High Added Value Without Additional Costs
The increasing use of granite in mechanical engineering is not so much due to the massive increase in the price of steel. Rather, it is because the added value for the machine tool achieved with a machine bed made of granite is possible at very little or no extra cost. This is proven by cost comparisons of well-known machine tool manufacturers in Germany and Europe.

The considerable gain in thermodynamic stability, vibration damping and long-term precision made possible by granite cannot be achieved with a cast iron or steel bed, or only at relatively high cost. For example, thermal errors can account for up to 75% of the total error of a machine, with compensation often attempted for by software – with moderate success. Due to its low thermal conductivity, granite is the better foundation for long-term precision.

With a tolerance of 1 μm, granite easily meets the flatness requirements according to DIN 876 for the degree of accuracy 00. With a value of 6 on the hardness scale 1 to 10, it is extremely hard, and with its specific weight of 2.8g/cm³ it almost reaches the value of aluminium. This also results in additional advantages such as higher feed rates, higher axis accelerations and an extension of the tool life for cutting machine tools. Thus, the change from a cast bed to a granite machine bed moves the machine tool in question into the high-end class in terms of precision and performance – at no extra cost.

Granite’s Improved Ecological Footprint
In contrast to materials such as steel or cast iron, natural stone does not have to be produced with a great deal of energy and using additives. Only relatively small amounts of energy are required for quarrying and surface treatment. This results in a superior ecological footprint, which even at the end of a machine’s life surpasses that of steel as a material. The granite bed can be the basis for a new machine or be used for completely different purposes such as shredding for road construction.

Nor are there any shortages of resources for granite. It is a deep rock formed from magma within the earth’s crust. It has ‘matured’ for millions of years and is available in very large quantities as a natural resource on almost all continents, including all of Europe.

Conclusion: The numerous demonstrable advantages of granite compared to steel or cast iron justify the increasing willingness of mechanical engineers to use this natural material as a foundation for high-precision, high-performance machine tools. Detailed information about granite properties, which are advantageous for machine tools and mechanical engineering, can be found in this further article.

A repeat measurement is a measurement of local flatness areas. The Repeat Measurement specification states that a measurement taken anywhere on the surface of a plate will repeat within the stated tolerance. Controlling local area flatness tighter than overall flatness guarantees a gradual change in surface flatness profile thereby minimizing local errors.

Most manufacturers, including imported brands, adhere to the Federal Specification of overall flatness tolerances but many overlook the repeat measurements. Many of the low value or budget plates available in the market today will not guarantee repeat measurements. A manufacturer who does not guarantee repeat measurements is NOT producing plates that meet the requirements of ASME B89.3.7-2013 or Federal Specification GGG-P-463c, or DIN 876, GB, JJS...

Both are critical to ensure a precision surface for accurate measurements. Flatness specification alone is not sufficient to guarantee measurement accuracy. Take as an example, a 36 X 48 Inspection Grade A surface plate, which meets ONLY the flatness specification of .000300". If the piece being checked bridges several peaks, and the gage being used is in a low spot, the measurement error could be the full tolerance in one area, 000300"! Actually, it can be much higher if the gage is resting on the slope of an incline.

Errors of .000600"-.000800" are possible, depending upon the severity of the slope, and the arm length of the gage being used. If this plate had a Repeat Measurement specification of .000050"F.I.R. then the measurement error would be less than .000050" regardless of where the measurement is taken on the plate. Another problem, which usually arises when an untrained technician attempts to resurface a plate on-site, is the use of Repeat Measurements alone to certify a plate.

The instruments that are used to verify repeatability are NOT designed to check overall flatness. When set to zero on a perfectly curved surface, they will continue to read zero, whether that surface is perfectly flat or perfectly concave or convex 1/2"! They simply verify the uniformity of the surface, not the flatness. Only a plate that meets both the flatness specification AND the repeat measurement specification truly meets the requirements of ASME B89.3.7-2013  or Federal Specification GGG-P-463c.

Ask us about or flatness specification and repeat measurement promise by calling +86 19969991659 or emailing INFO@ZHHIMG.COM

Yes, but they can only be guaranteed for a specific vertical temperature gradient. The effects of thermal expansion on the plate could easily cause a change in accuracy greater than the tolerance if there is a change in the gradient. In some cases, if the tolerance is tight enough, the heat absorbed from overhead lighting can cause enough of a gradient change over several hours.

Granite has a coefficient of thermal expansion of approximately .0000035 inches per inch per 1°F. As an example: A 36" x 48" x 8" surface plate has an accuracy of .000075" (1/2 of Grade AA) at a gradient of 0°F, the top and bottom are the same temperature. If the top of the plate warms up to the point where it is 1°F warmer than the bottom, the accuracy would change to .000275" convex ! Therefore, ordering a plate with a tolerance tighter than Laboratory Grade AA should only be considered if there is adequate climate control.

A surface plate should be supported at 3 points, ideally located 20% of the length in from the ends of the plate. Two supports should be located 20% of the width in from the long sides, and the remaining support should be centered. Only 3 points can rest solidly on anything but a precision surface.

The plate should be supported at these points during production, and it should be supported only at these three points while in use. Attempting to support the plate at more than three points will cause the plate to receive its support from various combinations of three points, which will not be the same 3 points on which it was supported during production. This will introduce errors as the plate deflects to conform to the new support arrangement. All zhhimg steel stands have support beams designed to line up with the proper support points.

If the plate is properly supported, precise leveling is only necessary if your application calls for it. Leveling is not necessary to maintain the accuracy of a properly supported plate.

Why Choose Granite for Machine Bases and Metrology Components?

The answer is 'yes' for almost every application. The advantages of granite include: No rust or corrosion, almost immune to warping, no compensating hump when nicked, longer wear life, smoother action, greater precision, virtually non-magnetic, low co-efficient of thermal expansion, and low maintenance cost.

Granite is a type of igneous rock quarried for its extreme strength, density, durability, and resistance to corrosion. But granite is also very versatile– it’s not just for squares and rectangles! In fact, Starrett Tru-Stone confidently works with granite components engineered in shapes, angles, and curves of all variations on a regular basis—with excellent outcomes.

Through our state of the art processing, cut surfaces can be exceptionally flat. These qualities make granite the ideal material to create custom-size and custom-design machine bases and metrology components. Granite is:

machineable
precisely flat when cut and finished
rust resistant
durable
long lasting
Granite components are also easy to clean. When creating custom designs, be sure to choose granite for its superior benefits.

STANDARDS / HIGH WEAR APPLICATIONS
The granite utilized by ZhongHui for our standard surface plate products has high quartz content, which provides greater resistance to wear and damage. Our Superior Black and Crystal Pink colors have low water absorption rates, minimizing the possibility of your precision gages rusting while setting on the plates. The colors of granite offered by ZhongHui result in less glare, which means less eyestrain for individuals using the plates. We have chosen our granite types while considering thermal expansion in an effort to keep this aspect minimal.

CUSTOM APPLICATIONS
When your application calls for a plate with custom shapes, threaded inserts, slots or other machining, you’ll want to select a material like Black Diabase. This natural material offers superior stiffness, excellent vibration dampening, and improved machinability.

Yes, if they are not too badly worn. Our factory setting and equipment allow the optimum conditions for proper plate calibration and rework if necessary. Generally, if a plate is within .001" of the required tolerance, it can be resurfaced on-site. If a plate is worn to the point where it is more than .001" out of tolerance, or if it is badly pitted or nicked, then it will need to be sent to the factory for grinding prior to relapping.

Great care should be exercised in selecting an on-site calibration and resurfacing technician. We urge you to use caution in selecting your calibration service. Ask for accreditation and verify the equipment that the technician will use has a National Inspection Institution traceable calibration. It takes many years to learn how to properly lap precision granite.

ZhongHui provides quick turn-around on calibrations performed in our factory. Send your plates in for calibration if possible. Your quality and reputation depend on the accuracy of your measurement instruments including surface plates!

Our black surface plates have a significantly higher density and are up to three times as stiff. Therefore, a plate made of the black does not need to be as thick as a granite plate of the same size to have equal or greater resistance to deflection. Reduced thickness means less weight and lower shipping costs.

Beware of others who use lower quality black granite in the same thickness. As stated above, properties of granite, like wood or metal, vary by material and color, and is not an accurate predictor of stiffness, hardness, or wear resistance. In fact, many types of black granite and diabase are very soft and not suitable for surface plate applications.

No. The specialized equipment and training necessary to rework these items requires that they be returned to the factory for calibration and rework.

Yes. Ceramic and granite have similar characteristics, and the methods used to calibrate and lap granite can be used with ceramic items as well. Ceramics are more difficult to lap than granite resulting in a higher cost.

Yes, provided that the inserts are recessed below the surface. If steel inserts are flush with, or above the surface plane, they must be spot-faced down before the plate can be lapped. If required, we can provide that service.

Yes. Steel inserts with the desired thread (English or metric) can be epoxy bonded into the plate at the desired locations. ZhongHui uses CNC machines to provide the tightest insert locations within +/- 0.005”. For less critical inserts, our locational tolerance for threaded inserts is ±.060". Other options include steel T-Bars and dovetail slots machined directly into the granite.

Inserts that are properly bonded using high strength epoxy and good workmanship will withstand a great deal of torsional and shear force. In a recent test, using 3/8"-16 threaded inserts, an independent testing laboratory measured the force required to pull an epoxy-bonded insert from a surface plate. Ten plates were tested. Out of these ten, in nine cases, the granite fractured first. The average load at the point of failure was 10,020 lbs. for gray granite and 12,310 lbs. for black. In the single case where an insert pulled free of the plate, the load at the point of failure was 12,990 lbs.! If a work piece forms a bridge across the insert and extreme torque is applied, it is possible to generate enough force to fracture the granite. Partially for this reason, ZhongHui gives guidelines for the maximum safe torque that can be applied the epoxy bonded inserts: https://www.zhhimg.com/standard-thread-inserts-product/

Yes, but only at our factory. At our plant, we can restore almost any plate to 'like-new' condition, usually for less than half the cost of replacing it. Damaged edges can be cosmetically patched, deep grooves, nicks, and pits can be ground out, and the attached supports can be replaced. In addition, we can modify your plate to increase its versatility by adding solid or threaded steel inserts and cutting slots or clamping lips, per your specifications.

Why Choose Granite?
Granite is a type of igneous rock formed in the Earth millions of years ago. The composition of igneous rock contained many minerals such as quartz that is extremely hard and wear-resistant. In addition to hardness and wear resistance granite has approximately half the coefficient of expansion as cast iron. As its volumetric weight is approximately one third that of cast iron, granite is easier to manoeuvre.

For machine bases and metrology components, black granite is the colour most used. Black granite has a higher percentage of quartz than other colours and is, therefore, the hardest wearing.

Granite is cost-effective, and cut surfaces can be exceptionally flat. Not only can it be hand lapped to achieve extremes of accuracy, but re-conditioning can be performed without moving the plate or table off-site. It is entirely a hand lapping operation and generally costs much less than re-conditioning a cast iron alternative.

These qualities make granite the ideal material to create custom-size and custom-design machine bases and metrology components such as the granite surface plate.

ZhongHui produces bespoke granite products that are created to support specific measurement requirements. These bespoke items vary from straight edges to tri squares. Due to the versatile nature of granite, the components can be produced to any size required; they are hard wearing and long-lasting.

Advantages of Granite Surface Plates
The importance of measuring on an even surface was established by British inventor Henry Maudsley in the 1800s. As a machine tool innovator, he determined that consistent production of parts required a solid surface for reliable measurements.

The industrial revolution created a demand for measuring surfaces, so engineering company Crown Windley created manufacturing standards. The standards for surface plates were first set by Crown in 1904 using metal. As the demand and cost for metal increased, alternative materials for the measuring surface were investigated.

In America, monument creator Wallace Herman established that black granite was an excellent surface plate material alternative to metal. As granite is non-magnetic and doesn’t rust, it soon became the preferred measuring surface.

A granite surface plate is an essential investment for laboratories and test facilities. A granite surface plate of 600 x 600 mm can be mounted on a support stand. The stands provide a working height of 34” (0.86m) with five adjustable points for levelling.

For reliable and consistent measurement results, a granite surface plate is crucial. As the surface is a smooth and stable plane, it enables instruments to be carefully manipulated.

The main advantages of granite surface plates are:

• Non-reflective
• Resistant to chemicals and corrosion
• Low coefficient of expansion compared with cart iron so less affected by temperature change
• Naturally rigid and hard-wearing
• The plane of the surface is unaffected if scratched
• Will not rust
• Non-magnetic
• Easy to clean and maintain
• Calibration and resurfacing can be done onsite
• Suitable for drilling for threaded support inserts
• High vibration damping

For many shops, inspection rooms and laboratories, precision granite surface plates are relied on as the basis for accurate measurement. Because every linear measurement depends on an accurate reference surface from which final dimensions are taken, surface plates provide the best reference plane for work inspection and layout prior to machining. They also are ideal bases for making height measurements and gaging surfaces. Further, a high degree of flatness, stability, overall quality and workmanship make them a good choice for mounting sophisticated mechanical, electronic and optical gaging systems. For any of these measurement processes, it is imperative to keep surface plates calibrated.

Repeat Measurements and Flatness
Both flatness and repeat measurements are critical to ensure a precision surface. Flatness can be considered as all points on the surface being contained within two parallel planes, the base plane and the roof plane. The measurement of distance between the planes is the overall flatness of the surface. This flatness measurement commonly carries a tolerance and may include a grade designation.

The flatness tolerances for three standard grades are defined in the federal specification as determined by the following formula:
Laboratory Grade AA = (40 + diagonal² / 25) x 0.000001 inch (unilateral)
Inspection Grade A = Laboratory Grade AA x 2
Tool Room Grade B = Laboratory Grade AA x 4

In addition to flatness, repeatability must be ensured. A repeat measurement is a measurement of local flatness areas. It is a measurement taken anywhere on the surface of a plate that will repeat within the stated tolerance. Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.

To ensure a surface plate meets both the flatness and repeat measurement specifications, manufacturers of granite surface plates should use Federal Specification GGG-P-463c as a basis for their specifications. This standard addresses repeat measurement accuracy, material properties of surface plate granites, surface finish, support point location, stiffness, acceptable methods of inspection and installation of threaded inserts.

Before a surface plate has worn beyond specification for overall flatness, it will show worn or wavy posts. Monthly inspection for repeat measurement errors using a repeat reading gage will identify wear spots. A repeat reading gage is a high-precision instrument that detects local error and can be displayed on a high magnification electronic amplifier.

Checking Plate Accuracy
By following a few simple guidelines, an investment in a granite surface plate should last for many years. Depending on plate usage, shop environment and required accuracy, frequency of checking the surface plate accuracy varies. A general rule of thumb is for a new plate to receive a full recalibration within one year of purchase. If the plate is used frequently, it is advisable to shorten this interval to six months.

Before a surface plate has worn beyond specification for overall flatness, it will show worn or wavy posts. Monthly inspection for repeat measurement errors using a repeat reading gage will identify wear spots. A repeat reading gage is a high-precision instrument that detects local error and can be displayed on a high magnification electronic amplifier.

An effective inspection program should include regular checks with an autocollimator, providing actual calibration of overall flatness traceable to National Institute of Standards and Technology (NIST). Comprehensive calibration by the manufacturer or an independent company is necessary from time to time.

Variations Between Calibrations
In some cases, there are variations between surface plate calibrations. Sometimes factors such as surface change resulting from wear, incorrect use of inspection equipment or use of noncalibrated equipment can account for these variations. The two most common factors, however, are temperature and support.

One of the most important variables is temperature. For instance, the surface might have been washed with a hot or cold solution prior to calibration and not allowed sufficient time to normalize. Other causes of temperature change include drafts of cold or hot air, direct sunlight, overhead lighting or other sources of radiant heat on the surface of the plate.

There also can be variations in the vertical temperature gradient between winter and summer. In some cases, the plate is not allowed sufficient time to normalize after shipment. It is a good idea to record the vertical gradient temperature at the time the calibration is performed.

Another common cause for calibration variation is a plate that is improperly supported. A surface plate should be supported at three points, ideally located 20% of the length in from the ends of the plate. Two supports should be located 20% of the width in from the long sides, and the remaining support should be centered.

Only three points can rest solidly on anything but a precision surface. Attempting to support the plate at more than three points will cause the plate to receive its support from various combinations of three points, which will not be the same three points on which it was supported during production. This will introduce errors as the plate deflects to conform to the new support arrangement. Consider using steel stands with support beams designed to line up with the proper support points. Stands for this purpose are generally available from the surface plate manufacturer.

If the plate is properly supported, precise leveling is only necessary if an application specifies it. Leveling is not necessary to maintain the accuracy of a properly supported plate.

It is important to keep the plate clean. Airborne abrasive dust is usually the greatest source of wear and tear on a plate, as it tends to embed in workpieces and the contact surfaces of gages. Cover plates to protect them from dust and damage. Wear life can be extended by covering the plate when not in use.

Extend Plate Life
Following a few guidelines will reduce wear on a granite surface plate and ultimately, extend its life.

First, it is important to keep the plate clean. Airborne abrasive dust is usually the greatest source of wear and tear on a plate, as it tends to embed in workpieces and the contact surfaces of gages.

It also is important to cover plates to protect it from dust and damage. Wear life can be extended by covering the plate when not in use.

Rotate the plate periodically so that a single area does not receive excessive use. Also, it is recommended to replace steel contact pads on gaging with carbide pads.

Avoid setting food or soft drinks on the plate. Many soft drinks contain either carbonic or phosphoric acid, which can dissolve the softer minerals and leave small pits in the surface.

Where to Relap
When a granite surface plate needs re-surfacing, consider whether to have this service performed on-site or at the calibration facility. It is always preferable to have the plate relapped at the factory or a dedicated facility. If, however, the plate is not too badly worn, generally within 0.001 inch of the required tolerance, it can be resurfaced on-site. If a plate is worn to the point where it is more than 0.001 inch out of tolerance, or if it is badly pitted or nicked, then it should be sent to the factory for grinding prior to relapping.

A calibration facility has the equipment and factory setting providing the optimum conditions for proper plate calibration and rework if necessary.

Great care should be exercised in selecting an on-site calibration and resurfacing technician. Ask for accreditation and verify the equipment that the technician will use has a NIST-traceable calibration. Experience also is an important factor, as it takes many years to learn how to correctly lap precision granite.

Critical measurements start with a precision granite surface plate as a baseline. By ensuring a reliable reference by using a properly calibrated surface plate, manufacturers have one of the essential tools for reliable measurements and better quality parts.

Checklist for Calibration Variations

1. The surface was washed with a hot or cold solution prior to calibration and was not allowed sufficient time to normalize.
2. The plate is improperly supported.
3. Temperature change.
4. Drafts.
5. Direct sunlight or other radiant heat on the surface of the plate. Be sure that overhead lighting is not heating the surface.
6. Variations in the vertical temperature gradient between winter and summer. If at all possible, know the vertical gradient temperature at the time the calibration is performed.
7. Plate not allowed sufficient time to normalize after shipment.
8. Improper use of inspection equipment or use of noncalibrated equipment.
9. Surface change resulting from wear.

Tech Tips
Because every linear measurement depends on an accurate reference surface from which final dimensions are taken, surface plates provide the best reference plane for work inspection and layout prior to machining.

Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.