Grinding operations can yield accurate sizes and surfaces that make the use of ceramic materials preferable to other materials that cannot hold such fine tolerances.

When a ceramic part is required in an application, it's sometimes necessary to perform grinding operations on a fully fired ceramic, as opposed to machining in the "green" state, which usually doesn't allow for high accuracy form or fit. Not only are these grinding operations necessary to enable the ceramic part to be used in its intended application, but they can yield accurate sizes and surfaces that make the use of ceramic preferable to other materials that cannot hold such fine tolerances.

However, ceramic grinding requires the use of machine tools that employ diamond wheels. The diamond wheels and the machine tools that use them are costly to buy and operate. Grinding fully fired ceramics is therefore usually a costly endeavor that is only pursued if it makes economic sense based on an improved value over a part made from an alternate material, or if is needed to ensure the application's success. Insaco's ability to perform centerless grinding on rods 24 hours a day without an operator present is an example of the application of automation to the grinding process and how it can improve productivity.

Historical Perspective

Since 1947, Insaco Inc. has been exclusively machining and polishing ceramic, sapphire, and glass. This specialized marketplace requires significant capital investment, and Insaco has a devoted group of 70 employees performing grinding and polishing operations using machine tools adapted specifically for the processing of these materials.

The materials most commonly machined and polished are amorphous, crystalline or a combination of both. They include a variety of glass and hard carbides, nitrides, and oxides. Some of these materials include:

• Fused silica or quartz
• Macor® and Zerodur®
• High-alumina ceramic
• Zirconia
• Silicon carbide and boron carbide
• Sapphire (single-crystal alumina)

Insaco's expertise originated with the business of making sapphire phonograph needles for 78-rpm records in the late 1940s, but this business quickly evolved toward diamond stylus tips. In order to survive, Insaco needed to transform into a job shop and adjust to markets as they evolved. The company adapted to the requirements of various applications and the continuous development of ceramic materials.

This business evolution started with the company moving from phonograph needles to sapphire yarn guides in the 1950s, and continued on to ceramic parts for electron tube manufacturing on the 1960s. In the 1970s, Insaco was given an opportunity to work in the medical field fabricating a custom part for the CAT scanner. This part allowed for a significant growth in CNC machining, reflecting Insaco's business philosophy of reinvestment in new equipment and technology.

Also in the 1970s, sapphire was becoming better understood and accepted as the "alumina you can see through." Sapphire was commonly used as watch crystal faces, and the process of polishing flat surfaces was generally known. However, crystal growth technologies were advancing and larger sapphire pieces were becoming available, allowing customers to create unusual designs that were previously thought impractical or impossible. This led to the development of sapphire used in the electro-optics industry. Due to customer inquiries in these new designs, Insaco worked to develop the capability to machine and polish cylindrical and spherical surfaces to an optical quality.

The 1990s brought Insaco into the business of processing large glass plates for the life sciences industry. This capacity was initially developed to help a customer accommodate its needs for polished glass plates for DNA sequencing. However, the quantity demands quickly required an increase in throughput. An investment in vertical machining centers allowed for large volumes to be processed efficiently. These capital investments led to the embrace of automation to further decrease costs and increase production.

Centerless Grinding

Centerless grinding is an operation where an unmounted circular rod is ground between a diamond wheel and a rubberized wheel. The rubberized wheel forces the part against the diamond wheel, and the grinding action reduces the diameter of the rod by up to .003 in. per pass. This very time-consuming operation traditionally required extensive "touch" time by the operator running the machine.

Insaco has applied automation in order to improve the efficiency and reduce the cost of centerless grinding. The centerless grinder is set up in a closed-loop conveying system, with the parts measured automatically. The machine then adjusts as necessary to take cylindrical parts to final size.

The idea for automated centerless grinding originated internally and Insaco's engineering team spent significant effort making it a reality. The development, testing and implementation has now allowed for this manufacturing operation to be completely automated, resulting in increased throughput and reduced labor costs.

For additional information, contact Insaco at P.O. Box 9006, Quakertown, PA 18951; call (215) 536-3500; fax (215) 536-7750; email sales@insaco.com; or visit www.insaco.com.

Links

• Insaco