MEMO

To: Dr. Hugh Jack

From: Matt Remelts

Subject: Sinter Metal Tour

Date: 4-8-97

Our tour of Sinter Metal on Tuesday, April 8, revealed a very versatile company. With a wealth of experience and product scope, they offer an attractive service that will fit our powdered metallurgy needs. I believe we must consider them our top contender for the contract. They provide in-house engineering and manufacturing services of accurately machined and fabricated powdered metal products. Sinter Metal is a somewhat vertically integrated company. They have a hand in the manufacturing process from design to mold making to machining to finishing. They buy the powder from a supplier.

Sinter Metal uses practically any steel alloy necessary to produce their products. They begin with powdered iron or steel blend and add the necessary amount of carbon, zinc, or other elements to obtain the desired mechanical properties. After the metal powder is mixed, it goes to the presses. Here, the powder is compressed to take the form of the product. The part is then checked for any defects or dimensional inaccuracies. The powder has not yet been bonded, however. It must now be sintered. In this process, the powdered metal granules are heated to the precise temperature at which they partially melt in order to form the bonds that will give the part its strength. During this process, the parts travel through a furnace on a belt that moves at five inches per minute. The first stage in the furnace is a 1200 degree F chamber in which the lube that covers the parts is burned off. The next chamber is 2100 degrees. The parts take about 30 to 40 minutes to travel through it. This is where the actual melting of the granules takes place. When they come out of the sintering chamber, the parts travel about 30 to 40 feet more to allow for cooling. As they exit the furnace the parts are still close to 200 degrees. During this process, Sinter Metal can also infiltrate the parts with copper. To do this, one or more small copper cylinders are placed in strategic locations on the part before they enter the furnace. The copper has a lower melting point that steel, so as the parts are heated, the copper melts first and fills in the porous steel before the steel fuses. This is a common method used to reduce to porosity of powdered metal parts.

After the sintering operation, some of the parts are coined. This is the process of restamping the sintered part in order to get a high tolerance dimension or better finish. Also, some parts require further machining such as drilling, tapping, and milling.

All in all, from these observations, I believe that Sinter Metal should be seriously considered as a potential supplier. They are a company with a wealth of experience and the market to prove it. They supervise all areas of design and manufacture and turn out a quality product as a result.