Avoid Bad Planning
A recent survey showed that one of the worst mistakes during a mold build is "bad planning." What can a moldmaker do to avoid this mistake?
Al Amazon, tool engineering manager, Tyco Electronics (Salem, NC). 'Bad planning' is a phrase that encompasses a multitude of sins. Bad planning can mean something as simple as not ordering the required steel on a timely basis, under-estimating your shop's capabilities or not fully understanding the various machine processes that will be involved to achieve the finished product. It has been my experience that poor planning is the result of not taking a systematic approach to mold construction.
First, planning cannot fully begin until a mold concept design is completed and approved. Without a design, one does not have the required information on mold size, steel selection, parting line locations, laminated segments, gate locations, etc. Second, leadtimes for all of the mold's purchased components must be known and taken into consideration to avoid problems in final assembly. Third, the individual scheduling the work in the shop needs to know all of the people and their various skill levels - who is out sick every Friday or whose wife is pregnant. They need to know all of the available shop equipment and the equipment's capabilities. Last but not least, once all of the known entities are identified and taken into consideration, this scheduling genius needs to estimate a fudge factor for the unknown entities - things such as power outages, unscheduled machine down time and Johnny Jones - your top man - quitting in the middle of the week and moving to Florida to start a charter fishing business.
Mike Louris, tooling engineer, Apple Computer (Cupertino, CA). The key to good mold planning starts by working with the customer while the product is still in the design stage. This allows the moldmaker, molder and part designer to produce a part that is functional and designed for manufacturing. Draft angles, slides, lifters, gate locations and parting lines should all be discussed at this time. A mold flow analysis should be done to assure that the part can be molded as designed. The part should be analyzed for potential areas of sink, warp, knit lines, etc. This up-front engineering ensures a functional part and dependable mold with the fewest number of changes during the mold build. It also reduces the number of times the mold needs to be sampled and modified before it is qualified to run production. The benefits include: shorter mold leadtime, high mold and part quality, and reduced part and mold cost.
Once this is established, it is important for the mold shop employees to meet and lay out a plan for the design and build process. At this time, the collective experience of the employees can be leveraged to develop an efficient and effective plan. It also allows everyone to take ownership in the process, which encourages cooperation throughout the mold project. A sound mold planning procedure is essential to success in today's competitive mold building environment.
Bud Harrelson, EDM operator, Hayes Industries (Houston, TX). We are a large plastic molder with a captive tool shop. We only work on things we will be molding, and we do about 85 percent of our own products. The remaining 15 percent we do for customers, but we control the mold. If we make it, we will shoot it. Our molds range from simple to complicated. Since the work force on the production side is often not terribly sophisticated in a technical sense, we have learned several things over the years.
The first one is keep it simple. The second one is keep it simple. We try to design reliability into all of our molds, beginning with the inserts that can easily be replaced at suspected failure points. As molds run, they evolve. We learn from each mistake, and then we try to design out the mistakes. There are a lot of resources available to us beyond our experience. One is to read publications like this one where we can learn from others. There are several websites on the Internet that we find useful as well.
Keeping an open mind, coupled with a willingness to seek help or advice is a good place to start. Lots of stuff can translate into more money made per shot. How many parts are you going to shoot? If it's in the hundreds, you may stay as basic as possible. Hot runners and hot sprues, while not inexpensive, can result in a reduction in cycle time that can dramatically improve the bottom line on a run. In those circumstances, easy repairability is key. You have to design that in. If it isn't running, it isn't making money. We are not experts. We just do the best we can and try to learn from each experience.
Amar Patel, project and design engineer, Product Development Technologies, Inc. (Lincolnshire, IL). I wholeheartedly agree that bad planning is the worst mistake to make during a mold build. The planning should be started at the part design stage where the customer expectations and application are discussed. The team should establish a plan in which they can meet these goals, which may require some trade-offs and negotiations. The team also should look at any future design changes that could affect the tool design. Proper planning can save a considerable amount of time and expense. The ideal situation is to find a moldmaker who has design engineering, tool design and molding capabilities within the organization. This allows the design engineer, the tooling designer, the shop and the molding process engineer to discuss the program and determine the best way to successfully transition a part into production.
Jean H. Kroes, owner of J.H. Kroes Consulting (Ottawa, Ontario). How do we plan? In small shops, often the manager/owner just does it in his head and then directs from memory. In larger shops, the managers get involved and things are put on paper according to their feel and knowledge. Good planning, however, and especially successful planning - namely plans that really are fruitful - should involve all workers. This means the machinists, the programmers and the designers. By knowing what is coming up the pipeline, they will be able to give their input on tight spots otherwise 'kept secret', i.e., where overtime suddenly will be required because there is some work left over for repairs or the special family day that the worker expected to take off three weeks hence, but had not yet told the manager about, can be avoided. Workers also have a better feel for actual time required for certain jobs. Knowing what is coming up will allow them to order the special cutter or drill, replace the broken ones in time, etc. Because of this feel, they may well be able to adjust jobs to fit other ones in between, whereas a plan drawn up just by management will be considered very rigid, often resulting in wasted time.
Those who read me often know what is coming up next: the importance of good communication among all involved. When do we need it, why do we need it, where do we need it? Talking and listening are the base ingredients for good plans. Remember to think outside the box to make the items of the plan fit well - a plan is only good if all workers involved understand it - not just the management!
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