HMC s Yield Big Gains For Mold Base Shop

This shop was pleasantly surprised to discover that, besides making chips faster, its new horizontal machining centers also enabled them to eliminate a time-consuming, secondary operation.

Case Study From: 2/15/2003 Modern Machine Shop

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Makino A99 machining centers

After adding a pair of Makino A99 machiningcenters to its shop, Special Mold Engineering has realized significant productivity gains.

Special Mold Engineering (SME), Inc. (Rochester Hills, Michigan) exclusively manufactures mold bases for a variety of clients with specialized production needs. In 2001, to reduce machining time and to improve its overall process, the company purchased two A99 horizontal machining centers manufactured by Makino (Mason, Ohio).

At that time, operations manager Eddie Elliott and vice president David MacDonald anticipated a significant increase in the shop’s productivity. But they were pleasantly surprised to discover that, besides making chips faster, the new machines also enabled them to eliminate a time-consuming, secondary operation.

With the shop’s previous process, Mr. Elliott needed to assign one operator for each CNC milling machine, and a total of four machine setups were necessary to complete each part. Finishing mold base features such as the insert cavities formerly required additional hours of jig grinding work. Under these circumstances, the shop’s production capacity was limited, and the leadtimes to customers typically ranged from 4 to 6 weeks.

Mr. Elliott and Mr. MacDonald also had some concerns about thermal growth problems that occurred because the ballscrews heated up on their existing machining centers during continuous operation. In addition, SME had experienced problems with heat-induced spindle growth that affected machining accuracy.

Since installing the A99 machines, however, the shop has reduced its overall processing time by approximately 40 percent. Typical lead times for customers have been reduced to about 2 weeks. “We can rough out mold bases 4 times faster now than we could before we got the A99s,” says Mr. Elliott. Additionally, the shop has reduced its time for finish machining by 200 to 400 percent.

Whereas three machine setups formerly were required for milling and one additional setup was necessary for jig grinding, SME currently needs only two setups to complete a mold base.

Because the A99 machine incorporates a ballscrew chilling system and an oil-cooled spindle, the shop has also eliminated the problems with accuracy caused by thermal growth. The A99 spindle core cooling system circulates temperature-regulated oil through the center of the spindle during operation. The cooling oil then circulates through holes in the inner bearing races to lubricate the machine bearings.

Because both of the A99 machines can be operated by a single person rather than the two operators previously needed, SME has also reduced its labor costs substantially.

The cumulative effect of increasing machining speeds and reducing setups and labor has been quite significant for SME’s overall business. The company is now able to handle a larger volume of work while providing faster delivery and better quality to its customers. These productivity gains support SME’s continuing growth in a highly competitive market.

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