Lean Machines.docx

1、Lean MachinesLean Machines Imagine a board game for manufacturing engineers where all the game pieces are assembly machines, conveyors, parts feeders, robots and other types of equipment. The game takes place in a Tier 2 auto parts plant that has adopted lean production principles. The objective is

2、to acquire the right type of assembly equipment while confronting management, operators and customers constantly chanting the lean manufacturing mantra of waste elimination. As lean initiatives become more popular, many engineers are playing that game every day. To thrive in that type of environment

3、, engineers must break the age-old habit of always wanting to buy the fastest machine equipped with the latest bells and whistles. The trick is to challenge complexity and balance the right amount of automation to meet lean objectives and customer needs. Lean manufacturing has been touted as the pan

4、acea for the production world. However, the idea of capital equipment expenditure in a lean system is viewed as an oxymoron by some observers. They question the role of automation in an environment they perceive to be the domain of manual assembly processes. Others misinterpret lean and forego quant

5、um improvements in productivity by making due with existing machines rather than purchasing additional automation systems. They feel that lean manufacturing means spending less on capital equipment. We have come across many companies that wish to short cut the critical addition of equipment, says Ri

6、chard Ligus, president of Rockford Consulting Group (Rockford, IL). A typical tactic is to purchase scheduling software based on theory of constraints. But, capital equipment plays an extremely important role in the success of a lean manufacturing implementation. I havent seen a project where equipm

7、ent wasnt needed. When his team of consultants arrive at a new assignment, Ligus says one of the first things they check is the age, technology generation and condition of capital equipment. We almost always find unbalanced capacity and underperforming equipment, notes Ligus, who says manufacturing

8、engineers have a tendency to overautomate. People seem to think lean means not spending any money on automated equipment, adds Chet Marchwinski, communications director of the Lean Enterprise Institute (Brookline, MA). Actually, you have to have someat the right level of automationor you cant implem

9、ent lean. However, it is often more difficult to justify capital equipment expenditure in a lean environment. Traditionally, capital equipment justification is based on projected utilization rates, and this thinking is deeply ingrained, not only in the minds of accountants, but in the minds of engin

10、eers and managers as well, says Don Penkala, president of Granite Bay Consulting Inc. (Granite Bay, CA). In a lean environment, waste elimination and lead time reduction are the key goals. These two measures are more customer-focused and do not require asset utilization rates that lead to expensive

11、overproduction, backlogs at each stage of manufacture and needless storage and material handling costs. Lean principles allow manufacturers to significantly boost throughput, reduce time to market and quickly increase capacity. Implementing a lean philosophy also has the potential to lower costs and

12、 improve product quality. Manufacturers that have adapted lean principles have achieved some dramatic results, such as reduced floor space and improved efficiency. For instance, Delphi Automotive Systems (Troy, MI) cut 42 feet out of the assembly line at its air conditioning compressor plant in Jagu

13、ariuna, Brazil. That minimized the walk path of operators by more than 40 percent. The Marvair division of Airxcel Inc. (Cordele, GA) recently reduced the space required to assemble its commercial air conditioners and heat pumps from 12,000 square feet to 6,000 square feet, a 50 percent reduction. A

14、t the same time, it reduced hours-per-unit from 9.28 to 5.19 for a 44 percent improvement.Lean Defined Lean manufacturing traces its roots to Toyota Motor Co. (Tokyo). The Japanese automaker developed its famous Toyota Production System more than 50 years ago. Today, hundreds of companies have adapt

15、ed it with varying degrees of success. Rick Harris, president of Harris Lean Systems Inc. (Stamping Ground, KY), says 30 percent to 40 percent of all manufacturers in the United States claim to be implementing lean principles. However, only 5 percent are truly implementing lean manufacturing, claims

16、 Harris, who formerly served as manager of final vehicle assembly at Toyota Motor Manufacturing Inc. (Georgetown, KY) . Lean manufacturing is most common in the auto industry, but companies in other industries ranging from electronics to furniture, have successfully modified its basic principles. Th

17、ere are pockets of companies in every industry that are doing it best, Harris points out. No matter what type of product is being assembled, continuous improvement, customer focus, one-piece flow and waste reduction play a key role in lean manufacturing. The goal is to eliminate nonvalue-added activ

18、ities that prevent a one-piece flow of product. Lean thinking focuses on value-added flow and the efficiency of the overall system, says Dr. Jeffrey Liker, director of the Lean Program Office and the Japan Technology Management Program at the University of Michigan (Ann Arbor, MI). Lean manufacturin

19、g is a manufacturing philosophy that shortens the time between the customer order and the product build and shipment by eliminating sources of waste. No matter how its defined, lean is a concept that attacks waste within a plant or company. In a lean methodology, waste elimination results in cost re

20、duction. Waste is anything that does not contribute to transforming a part to your customers needs, says Liker. The No. 1 cause of waste is the failure to recognize that it is there. There are seven types of manufacturing waste: production over immediate demand; excess work in process and finished g

21、oods inventories; scrap, repairs and rejects; unnecessary motion; excessive processing; wait time; and unnecessary transportation. Lean production is aimed at the elimination of waste in every area of production, including customer relations, product design, supplier networks and factory management,

22、 says Dr. David Cochran, director of the Production System Design Laboratory at Massachusetts Institute of Technology (MIT, Cambridge, MA). Its goal is to incorporate less human effort, less inventory, less time to develop products and less space to become highly responsive to customer demand while

23、producing top quality products in the most efficient and economical manner possible. According to Granite Bay Consultings Penkala, capital equipment expenditure in a lean environment should be justified based on two factors: the amount of manufacturing waste eliminated and the reduction in productio

24、n lead Arial. Waste elimination, which includes product quality improvement, and lead time reduction are the most important factors to consider, says Penkala. Productivity improvements and labor cost reduction are internal measures and the least important.Time Factors Besides eliminating waste, lean

25、 production initiatives focus on reducing lead time, which is the total time a customer must wait to receive a product after placing an order. Takt time forms the heartbeat of any lean system. It sets the pace of production to match the rate of customer demand. Takt time is determined by dividing th

26、e available production time by the rate of customer demand. For example, if an automotive OEM demands 320 fuel pumps per day and a Tier 2 parts plant operates two shifts a day for a total of 960 minutes, the takt time is 3 minutes. Ideally, in a lean environment, equipment will operate at a rate det

27、ermined by forecasted customer demand, says Penkala. This is contrary to justification based on high utilization rates. Customer demand, including takt time, rapid response (delivery) and quality improvement should play a major role in capital equipment justification. Lean experts claim it is easier

28、 to meet customer demand with simpler, dedicated pieces of equipment. Complex equipment may not be the answer, warns Rick Harris. Its better to look for a low capital piece of equipment that will make what your customer wants, with the ability to produce more if the customer demands. The lower the c

29、omplexity, the better off you will be in the long run. Unfortunately, many machine builders are in business to make complex machines. Too many people want to sell a Cadillac when a Chevy will do. According to Harris, coauthor of Creating Continuous Flow (published by the Lean Enterprise Institute),

30、machine time should be closely calibrated to takt time. In a world where machines are not completely capable or available and demand does change, it is best to target effective cycle Arial for every machine in the cell at no more than 80 percent of the fastesthighest volumetakt time, he explains. Th

31、is ensures that operators will not have to wait for machines to finish cycling the next time they come around to go through the work elements. It also provides a bit of extra capacity to accommodate some demand increases without the need to add capital equipment or pay large amounts of overtime. Har

32、ris and other lean experts point out that engineers have a tendency to buy more capacity than is needed. John Shook, a Dexter, MI-based senior advisor to the Lean Enterprise Institute, says manufacturing engineers should consider market size and demand projections when buying new equipment. Look for smaller increments of capacity, suggests Shook, who formerly served as deputy general manager of Toyotas Supplier Support Center. So often, demand forecasts tend to be wrong. We just dont know what demand is going to be. The pace of production should be