Original Date: 08/30/2004
Revision Date: 01/18/2007
Information : Semi-Lights Out Manufacturing
TOMAK Precision performs a wide range of precision machining and grinding, particularly for the aerospace industry. When the company decided to produce skull pins, which are used in the medical industry, it quickly realized that a change in manufacturing processes was needed to be cost effective. A Semi-Lights Out Manufacturing process was developed which ultimately proved very successful and profitable.
TOMAK Precision has had a long history of manufacturing parts requiring precision machining and grinding. While a significant portion of its business supports the aerospace industry, TOMAK Precision actively pursues other markets to expand its business. The company began a partnership with a medical company that was interested in placing orders for skull pins (Figure 3-1). Before a final agreement was reached, TOMAK Precision recommended a test run be performed to ensure the product could be manufactured to meet the customer’s requirements and produced at a reasonable cost. The customer made an initial investment of just under $6,000; however, the cost of the work was nearly double that amount. Rather than abandon this line of work, TOMAK Precision re-examined its processes and worked to develop a plan that could make the partnership successful.
During the test run period, it was determined that the cycle time to produce the part was approximately 58 seconds. Based on the machine operator’s wage rate and the material cost, it was determined that the unit cost was at least $1.30. Given that the customer was only willing to pay $1.08 per part, TOMAK Precision recognized that cost reduction measures were needed. Although TOMAK Precision considered producing the parts in a lights out (non-attended) mode, it became apparent that chip control and cutoff nib removal would be a problem. Although a simple shield was used to protect the insert (tool) from damage, the material and shape of the skull pin generated a large chip nest and precluded running the operation in a lights out mode; hence, a compromise solution was developed. Small modifications were made to the Computer Numerically Controlled (CNC) machining equipment, and tooling data was programmed into the machine that alerted the operator when tool life was about to be exceeded. Under these conditions, TOMAK Precision conducted a small run of 10 units in a Semi-Lights Out (semi-attended) mode to determine if the approach would be feasible. As the company gained confidence using this process, unattended runs for periods of a few hours were conducted as they increased the number of parts from 10 to 70.
As a result of making changes to its tooling and performing its machining process in a Semi-Lights Out mode, TOMAK Precision reduced cycle times, resulting in almost a 50% increase in production quantity and allowing the company to be profitable. TOMAK Precision and its customer reached an agreement that led to the production of 80,000 skull pins in 2003. With its continued effort to improve on customer partnerships, TOMAK Precision estimates it will produce 120,000 parts in future years.
Figure 3-1. Skull Pins
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