How Best Shops Reduce Cycle Times

Benchmarking data highlights the key factors.

IN THE 2006 AMERICAN MACHINIST Benchmarking Survey we asked respondents to indicate their average machining cycle times (from the start of a cut to completion) for a typical product and how those times have changed from three years ago. The data indicates that all shops saw a decrease in cycle times, with an average of 25 percent. Independent job shops reported the greatest decrease — 40 percent to 50 percent.

The survey did not ask how shops reduced cycle times, but it did ask about the tools and techniques that shops used to contribute to reduced cycle times. By examining the differences between the top performing, benchmark shops and all other shops in using those tools and techniques, a pattern emerges on how shops reduce cycle times.

Perhaps the most important tool that shops use is an organized approach to continually improve the way they operate. Top shops are twice as likely to use formal continuous improvement programs — 51 percent of the top shops have formal programs in place compared with 27.4 percent of all other shops. Additionally, 88.2 percent of the top shops use lean manufacturing techniques, while half that number — 41.1 percent — of all other shops do. Reduced cycle times are a result of those programs.

Some of the most common techniques used to reduce cycle times involve CAM and other software tools that optimize toolpaths and maximize cutting time. Of the top shops, 96.1 percent use CAM packages, while 81.4 percent of the other shops do, and 47.1 percent of top shops use proprietary software tools compared with only 19.4 percent of other shops. Offline toolpath optimization and verification offer substantial improvements in this area.

The survey asked if shops deliberately try to maximize cutting. Of the top shops, 74.5 percent said "Yes," while 39.8 percent — just over half — of the other shops did.

Also, 76.5 percent of top shops try tomaximize machine uptime compared to 36.7 percent of the other shops.

Tool manufacturers continually develop tools that can reduce cycle times dramatically, and the top shops are using them. The average top shop spends $125,000 a year on tooling, four times as much as other shops that indicated they spend about $30,000 a year on tooling.

In 2005, capital spending as a percentage of sales averaged 5.0 percent for the top shops, as compared with 3.0 percent for the other shops, and 61.7 percent of the top shops said they expect to increase their capital spending in 2006 as compared with only 46.1 percent of the other shops. New equipment has the potential to reduce cycle times in addition to providing other benefits, but new equipment is expensive. Apparently, top shops are either more willing or more able to make those types of investments.

Reducing cycle times is a worthwhile goal because every minute saved in the production process has the potential of making the business more profitable, but the key word is "potential." What benefit is realized if a machine cuts a part in less time if the machine then sits idle waiting for an operator, who may be busy servicing another machine, to remove the part and chuck up a new workpiece? If a shop is going to invest the time and money to reduce cycle times, then it should also invest time and money in improving the overall production process so that it can then reap the benefits of reduced cycle time. And that is what the top shops are doing.

The use of automation and robotics can maximize total throughput on a production system. Of the top shops,43.1 percent said they use automation, compared with only 21.2 percent of the other shops. Further, 27.5 percent of the top shops use robotics, but only 11.9 percent of other shops do.

It all goes back to the most important tool — a program and commitment to continually improving the total production process. Cycle times certainly need to be considered, but cycle time improvement without overall production process improvement will not improve a business's bottom line.

(For related information, see the following articles either in print or on-line:
"A ROUGH GUIDE TO BETTER MILLING", American Machinist, July, 2006, pg. 42, also at www.americanmachinist.com/304/Issue/Article/False/21630/Issue.
"ICING HARD TURNING", American Machinist, November, 2006, pg. 38, also at www.americanmachinist.com/304/Issue/Article/False/43187/.
"GET A PROCESS ENGINEER FOR FREE", December, 2006, pg. 40, also at www.americanmachinist.com/304/Issue/Article/False/43811/.
And, "ADAPTIVE CONTROLS SAVE TOOLS AND TIME" in this issue.)

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