Surface plates should be checked on a regular basis for wear using a repeat reading gage with a manual indicator. Generally, long before a surface plate has worn beyond specifications for overall flatness, it will show worn or wavy spots, which will produce measurement errors. The reading gage will readily detect these error-causing areas.
Also note that actual calibration of overall flatness traceable to N.I.S.T. can be performed periodically using an autocollimator.Simply set the gage on the plate and zero it at any point on the table. Move the gage over the plate and if there are hand movements in the indicator more than .000025” for a “AA” plate, .000050” for an “A” plate or .000100” for a “B” grade plate then you have indication that the plate may have some high and low spots and be out of tolerance. Specifically, the tolerance must repeat from side to side within the specified tolerance range in order to be an accurate plate.
When inspection indicates that the overall accuracy of a surface plate is out of tolerance, the plate should be relapped to restore it to its original accuracy. Even with normal use a plate should be calibrated on an established cycle, whether it be 1, 2 or 3 years, depending on frequency of use.
The granite surface plate was invaluable for ensuring flatness accuracy in the 1950's and provides the same benefit today. Following the simple rules for maintaining your plates will provide you with precise measurement readings in your manufacturing process.
Because a surface plate is a standard or “0” reference point, there are many uses for surface plates. Whether alongside manufacturing or in final inspection, granite surface plates are vital for quality control.
1. When using a height gage on the plate you must “0” that gage anywhere on the surface plate with a gage block. Remove the gage block and you can check any of your parts to see if they are flat. Large automotive manufacturers plates to check for warpage of chassis' or crankshafts, as does the aircraft industry etc. Usage for precision granite is virtually unlimited.
2. Do not use granite surface plates as workbenches or lunch tables. Dropping wrenches or hammers on plates can chip and nick the surface, and spilling coffee or drinks on granite can cause permanent stains. Grease from food particles will do the same.
3. Be sure to set your work piece to be measured down gently on the plate, as a sudden jolt or blow to the plate with a heavy metal object can chip or nick the surface. Also, when inspecting work pieces, especially small parts, try to used different areas of the surface plate because using the same spot over and over, year after year, will wear a “hole” in the plate.
4. When using threaded inserts in a granite surface plate, use the minimum torque required on hold down bolts, but do not exceed the limits noted on the caution label attached to the plate which came with the threaded insert.
The granite surface plate is a precision piece of equipment and must be properly installed and maintained. Before use, be sure the granite surface plate is always used on the support system furnished with the plate.
This will normally be a hard rubber pad attached to the bottom of the plate forming a non-distortable 3-point support system. The pads are installed during manufacturing and the plate rests on them throughout lapping, inspection and shipping. They are a critical factor in surface plate accuracy and must not be removed. Plates up to and including 6' wide x 12' long are furnished with this non-distortable 3-point support system.
When mounting the plate on a stand, be sure only the pads are resting the stand. Never support the plate by the ledges or under its four corners as this will completely void the guarantee of accuracy.
Plates larger than 6' wide x 12' long are supported on multiple support points (6 or more points) consisting of granite pedestals and leveling wedges. The number of support points and positioning is determined by the size of the plate. The height of the granite pedestals, or even if they are used, is determined by the thickness of the plate and overall working height desired.
Nylon slings are highly suggested when lifting precision granite. If you must use a forklift to move the granite surface plate, always have protective padding between the metal forks and the granite.
Once set-up, plates do not require extensive care and maintenance. However, it is important to follow some basic rules. Primarily, keeping the surface clean and free from buildup of dust, dirt, grease, grime and other foreign particles will maintain accurate tool readings and extend the life of the plate. Environment and usage have much to do with the frequency of cleaning; however, as a rule, you should clean a plate daily if it is used each day. Consult your supplier for a good surface plate cleaner and if the plate is not used for an extended period of time, it should be covered with a surface plate cover.
All precision granite are not the same. Depending on the type and different wear characteristics, we have Black Granite Surface Plate and Starrett Crystal Pink Granite Surface Plate.
The Black Granite Surface Plate or Diabase is harder than the other granites. The modulus of elasticity is 9.5 x 10 to 6th power comparing to the Crystal Pink which is 3.8 x 10 to the 6th power. However, due to the quartz content of 32% in the Crystal Pink it will outlast the Black 5 to 1. The quartz content is the determining factor in the wearability of granite. Black granite is used primarily for its load bearing capabilities. With any specific weight the Black will be thinner than the “Crystal Pink” because it is literally just a piece of “rock” with no particular mineral content. Whereas, the quartz content of the Crystal Pink permits the instruments to slide much easier without any risk of wearing the plate. In general, Crystal Pink does not carry the load of the black, but its thickness can be compensated to carry the same load.
Starrett Tru-Stone Division provides solutions for your precision metrology applications. Products and services range from standard granite surface plate, angle plate and metrology accessories to engineering collaboration for unique solutions and complex assemblies. Our skilled technicians build your product in our state-of-the-art, environmentally controlled manufacturing facility.
Starrett Tru-Stone Division provides solutions for your precision metrology applications. Products and services range from standard granite surface plate, angle plate and metrology accessories to engineering collaboration for unique solutions and complex assemblies. Our skilled technicians build your product in our state-of-the-art, environmentally controlled manufacturing facility.
On January 19th Senator Al Franken visited the Starrett Tru-Stone Technologies facility in Waite Park Minnesota. It has become recognized by both government and industry that there is a critical shortage of skilled employees to fill job openings. The Senator had been traveling the state to visit with manufacturers in an effort to address the skills gap between the students that the schools are graduating and what the industry needs to fill its open positions. Senator Franken made two stops in St. Cloud on his tour through the state. One stop was at the Starrett Tru-Stone Technologies facility and the other at the New Flyer Bus Company. The Senator was very complimentary of the Tru-Stone facility and impressed with the type of work that the people performed at Tru-Stone. He was quoted by the local radio station as saying “the place well run and is doing very, very, very high precision stuff in granite that is being sent all over the world. I am very interested in workforce training, making sure that manufacturing sites like this one have employees with the right skills not only now in the present but also in the future long term.”
Like many companies, finding good employees is key to our success and critical for our continued growth. The need to fill skilled positions in engineering, machining and fabrication has grown significantly since the economic recovery began. We along with members of the Central Minnesota Manufacturers Association, that were also present, were able to spend a significant amount of time talking to the Senator about the need for more programs like Minnesota’s Project Lead the Way which helps in getting high school students interested in engineering and manufacturing. We welcome Senator Franken’s strong efforts to bridge the gap of providing good qualified employees to industry and good paying jobs to employees, and we of course we enjoyed showcasing the great work that Starrett employees perform every day.
Starrett Precision Granite Division provides solutions for your precision metrology applications. Products and services range from standard granite surface plate, angle plate and metrology accessories to engineering collaboration for unique solutions and complex assemblies. Our skilled technicians build your product in our state-of-the-art, environmentally controlled manufacturing facility.
There are big things happening at Precision Granite Division in Waite Park Minnesota. Last summer Starrett management approved a proposal to invest nearly $3.5 million dollars in the Tru-Stone facility in fiscal year 2012. The largest part of that investment was 17,600 sq. ft. expansion of the facility. The addition will bring the total facility to about 108,000 sq. ft. and provide expanded room for lapping and assembly labs. It will also house shipping and provide additional room for storage. The new area will have more high bay manufacturing area with better lighting, better cranes, including a much needed higher capacity 25 ton crane It will also become the new setting and inspection area and probably most significantly, it will house our new 5 axis mill.
The new 5 axis mill mentioned earlier is being built by CMS Brembana of Italy. The new mill will have a working envelope of 25ft x 13ft x 4.5 ft. The larger work envelop with the 5 axis capability and the integrated tool changer will allow us to work on bigger pieces without having to roll them over to reposition them to be worked or wait for an operator to change the tools. Additionally the mill will run nearly twice as fast and nearly 3 times more accurate than the current large mills we have in place today. It also brings the ability for us to drill and tap inserts in place for better accuracy on large pieces of granite, something that our customers want and we will finally be able to provide. In all, the new mill will be safer for the operators, improve our capacity, throughput time, cost and quality.
Once we are cleared to occupy the new building, shipping will relocate to their new area. The space they were in will be used to expand the clean room to better grow the semiconductor business and other “clean critical” assembly operations. And finally we will be installing a water cleaning system. This will pull the “mud” out of the of the process water so the machines will run with cleaner recycled water.
We hope to have everything completed in June of 2012. The investment will provide additional room for growth, better more accurate processing and position the Precision Granite division to maintain its leadership position well into the future.
Micrometer combines the double contact of a slide caliper with a precision screw adjustment.
Developments in precision measurement have made modern hand tools more accurate and easier to read. Reviewing basic tips on the use of machinist tools can help machinist’s use the tools to their full potential and ultimately save time, reduce errors and increase productivity.
The precision micrometer is the most accurate handheld tool available to skilled operators. Some examples of micrometers include digital, vernier, inside and bench.
Micrometer combines the double contact of a slide caliper with a precision screw adjustment that may be read with great accuracy. To use the instrument, the work piece is placed against the anvil with the left hand while the spindle is turned with the thumb and index finger of the right hand. The measurement should not be forced, as light contact pressure ensures a correct reading.
Starrett will be at Quality Expo on March 14 and 15, 2012 in Fort Worth, TX - Booth# 823.
Click here to register
Starrett will be featuring its new force measurement systems and borescope along with its prestigious gages.
Starrett force measurement systems provide you with a reliable, accurate and easy-to-use solution for applications ranging from determining simple peak load measurement, load/extension at limits, or more complex break determination.
Starrett 698 and 699 Video Borescopes are ideal for inspection of inaccessible areas. Applications include viewing hard-to-see areas during machining operations, inspection of internal parts of engines and machinery, A/C systems, and interior structures of walls.
Stop by Starrett Booth# 823 for other exciting products!
The 2012 General Electric Superbowl Commercial featured Starrett 120A Dial Caliper. Starrett gages are used to build turbines that power America.
This Starrett 120A Dial Caliper is one of the handiest measuring tools available, used by mechanics and toolmakers everywhere.
Features
-
Direct reading, reliable and accurate
-
Hardened stainless steel bar, measuring surfaces, rack, gears and depth rod insure long life.
-
Sharp, clear dial graduations of .001"– .100" in one revolution for easy readability
-
Knife-edge contacts for both inside and outside measurements
-
The thumb-operated, fine adjustment roll permits one hand use.
-
Complete with Knurled Lock screw for dial bezel and for holding the sliding jaw in position
Starrett force measurement systems provide you with a reliable, accurate and easy-to-use solution for applications ranging from determining simple peak load measurement, load/extension at limits, or more complex break determination.
3 Applications of Force Measurement System
Production Management
With emphasis on lean manufacturing its important your capital equipment can be in the lab or the production floor and is simple to use, allowing focus on increased throughput, improved manufacturing yields, and better productivity.
Quality Management
Manage quality by using equipment that meets your testing and performance specifications. A Force Measurement System provides consistent results and produces empirical data that correlates with your legacy data.
Engineering Management
Use force measurement equipment to accurately validate material properties, products, safety, and conformance to industrial and internationally recognized testing standards such as ASTM, ISO, BS, and TAPPI.
