Material change increases productivity and cuts costs

G.W. Lisk gains productivity and machinability with a change of material.


Machinability at G.W. Lisk Co. (www.gwlisk.com) posed a problem with two different alloys specified for two critical parts the shop made for use in hightemperature applications. A wellknown manufacturer of solenoids, valves, linear variable differential

transducers and flame arresters, Lisk experienced poor results trying to machine two valve components — one made from Type 431 stainless steel and the other from Type 15Cr-5Ni stainless.

After consulting with Bob Mohr, a regional metallurgist for Carpenter Technology Corp. (www.cartech.com), Lisk incorporated Carpenter's Micro-Melt Type 431-FM stainless steel and its Project 70+ 15Cr-5Ni stainless. These materials improved machinability for both valve components while retaining essential material properties.

Prior to incorporating Micro-Melt for the first valve part, machining cycle times ran 5 minutes and 6 seconds, which was too slow for meeting a production rate of 1,500 parts per week for four months. Depending on barstock consistency, the shop spent from 93 to 131 hours making 1,000 parts.

In addition, carbide tools such as end mills, T-slot cutters and drills broke frequently or required excessive maintenance. Also, milling created burrs, forcing Lisk to manually remove them using abrasive brushes at a substantial cost in labor and productivity.

Micro-Melt let Lisk operators reduce part cycle time to 3.5 minutes and machine 1,000 parts in 55 to 58 hours. The material, which operators found significantly easier to cut, doubled tool life and reduced manual deburring time to a minimum. According to Steve Cheney, purchasing manager at Lisk, Micro-Melt slashed machining costs for the part by about 40 percent.

For the second valve part, Lisk had to send the initial standard stainless steel material it used to a commercial heat treater for aging and heat treatment prior to machining. Carbide tools broke prematurely or required frequent maintenance while cutting the material, and downtime for tool sharpening, along with escalating labor costs involved, hindered productivity.

Carpenter's Project 70+ material, which is aged to condition at the mill, eliminated the need for Lisk to outsource for aging and heat treatment. Since incorporating the new material, Dave Phillips, CNC department supervisor at Lisk, estimates the shop more than doubled tool life, increased productivity by 35 percent, and saved a comparable percentage in costs for labor and machine downtime associated with maintenance and tool sharpening.

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