A 3-D CAD modeling case study: The DFM defines the supply chain that guides the DFM

Disclaimer: This case study of a coffee maker’s sheet metal cabinet features a pair of inventors doing their best at bringing a new product to market. The result was an award-winning product design in 2018. Over several years, they gained experience in our fabrication trade, sometimes painfully. It is very brave of them to share this with us.

Editor’s Note: The author’s explorations in design for manufacturability (DFM) are presented as an example of the kind of effort that goes into a DFM project, particularly one involving an industrial design (ID) team that is committed to a vision.

In the previous edition of this column (“A 3-D CAD modeling case study: Avoid DFM myopia,” Precision Matters, The FABRICATOR®, November 2018, p. 60), the cost of development for the brewer skyrocketed when the cover and chassis system had to be—yet again—redesigned and reprototyped. The root cause of this error was approval of shape over function. In other words, the DFM team had satisfied both the schedule and the industrial design, but failed to consider the structural consequences of thin sheet metal.

Throughout this story, someone in the supply chain was aware and yet errors were made. How can a job shop prevent its customers from making bad decisions? How can it help customers succeed? Perhaps Voga’s story offers some hints.

Three Is a Charm

As related over the previous 11 episodes, the patented Ground Control™ technology (see Figure 1) has been at the heart of at least three approaches to twin brewer cabinetry. The need to physically experience the operation of the machine demanded physical prototypes. CAD simulation was employed, but it wasn’t sufficient to evaluate this kind of hands-on equipment.

The first approach was literally a laboratory apparatus, suitable for proof of technology but not at all commercial. The second cabinet was an industrial designer’s shape that was tossed at the fabricators with “make it your way” hopeful instructions. The fabricators’ cabinet designs were buildable on their production line, but not usable for final assembly or service on Voga’s production line. The third cabinet design project was launched with rather expensive lessons learned in mind. This time, in-house CAD resources were rigorously used to refine and document the design for manufacturing.

The third cabinet project for this coffee brewer required three prototyping repeats. Each prototype was supposed to be the peat, not the re-peat. More specifically, each prototype project was launched and completed with the intent of taking it to market. Sadly, each prototype turned out to be merely an incremental improvement. The first prototype suffered from pressures of schedule. Industrial design goals were met, but haste in DFM resulted in flimsy parts. The second prototype had a good exterior, but asymmetrical plumbing on the interior resulted in noticeable differences in brewing between the left and right stations. The third prototype, pretty much as described in the previous episode, made it into production in 2016. If you’ve followed all 12 episodes, you know the tribulations and trials in the trail of the twin brewer.

Since the release of their twin brewer, Voga has successfully released the Cyclops® line of Ground Control brewers (see Figure 2). Cyclops is functionally half of its predecessor. Its award-winning design has been well-received in the specialty coffee industry. As we conclude this discussion of cabinetry, we congratulate Voga Coffee on their ongoing business success. They have two brewers on the market, and the third product (to be released in the near future) is well underway.

In the product development trade, you have good results and other results. This has been a story about product development with mixed results. It has a happy ending, but wouldn’t it have been nice to skip all the false starts and dead ends? Wasted money is sad. Wasted time is tragic.

What Worked

The second brewer, Cyclops, worked as a product line. Upon demonstration in its market, it was almost instantly a success. It provided great flavor control. It was targeted for a specific market; the physical size and brewing capacity appealed to a wider range of end users. It was less complicated and less expensive. The development team had great clarity about the internal components and the characteristics of their ownership. The main development challenges were in packaging and scheduling.

As a practice session, the first brewer project was a glorious success. Although not as successful as the second product in their line, the first product worked in several ways. Perhaps most important, it performed well enough to sustain the development of the second brewer. The development of the first brewer’s cabinet has been the topic of this series of articles.

The twin cabinet’s development had two compelling results. It was dramatic during the brewing cycle and it was mildly fascinating to study when idle. To the outside world, this large brewer was imposing and heavy duty. Internally, there were several little secrets that have been identified but not corrected pending larger demand from the market. That stack of petty problems led to a flood of innovation in the next product line as “constraints were lifted” and a new beginning was begun.

The experience of producing the first finished product was useful for training in the following skill sets.

Schedule Estimating. How long does a project like this take? Considerations include design, documentation, budgeting, scheduling, fabrication, assembly, and testing. The first time around, a target schedule was set, but it relied heavily on guesswork. For the development of the second brewer, they predicted the schedule with fair results. The brewer shipped in the same quarter as predicted. To do this, they had to master trade nuance. “We can do that in six weeks” is not the same as “You will have that in six weeks.” It also might mean “We can’t possibly start on that for at least six weeks.”

Budget Estimating. What should it cost? After buying several variations from several suppliers, the client’s expectations and understanding of costs become clearer. Reading between the lines in vendor correspondence becomes automatic. On one hand, a supplier’s response to an RFQ may be prompt, clearly explained, and encouraging—a perfect fit between all parties. On the other hand, a vendor that is not really interested in or not qualified to perform the work may be slow to reply, reply with large values, or reply with ambiguity.

Dog Spotting. This is the talent of recognizing things that are not right. Sometimes discovery of an unintentional error can save the day. For example, an easy way to check on quality is to stack the parts and see how they compare. If the stack looks like a deck of cards, the parts are likely consistent and probably good. If the pile has gaps, the parts have flaws, and that is probably bad.

In the supply chain area, it is important to be skeptical of a price quote that is very low compared to others received for the same RFQ. Give the vendor an opportunity to verify the low bid. However, even with confirmation, is that vendor automatically part of the supply chain team? Is there flexibility in determining vendors, or does price drive the decision?

As rookies in the competitive bidding circuit, our trainees with the coffee maker company used low price as the best adviser when making selections. Today the policy is much different. When all “other things” are considered equal, price is relegated to the tie-breaker role. Other things considered before price include the trustworthiness and experience of the supplier.

Supply Chain Building. This is the most important thing that is built. The products’ reputation depends on a team of suppliers who are unaware of their relationship to each other. Our neophyte manufacturers of brewers started with an expectation that their supply chain would self-organize. They wanted a single source to manage the conversion of invention into a commercial design. They wanted to Google a supply chain and receive the item just as they dreamed it.

That delusion was dispelled over the course of bringing the first brewer into production. They learned that their product involved several distinct trades.

Trade Skills Comparing. This is the secret language of supply chains. Buzzwords like “precision tolerances” are interesting when comparing trades. Without planning for it, our heroes built a supply chain for glass, sheet metal, precision machining, injection molding, metal spinning, precision tube bending, welding, graining, painting, electronics, and software. That is a complex supply chain management chore.

Delivery Scheduling. This is the inventory game. Adapt to prevailing conditions; keep the ultimate delivery date in mind. In some cases, one trade must complete their work before the next can start. All demands on the supply chain must be satisfied before the brewer can ship.

Vendor Selecting. Find a team of strangers who dovetail in production rate, reliability, and availability. Our boys have learned that within each trade, services differ. Picking the perfect vendor requires an understanding of both the short- and long-term goals for the batch of product being built.

High-capacity shops are well-suited for cost-optimized manufacturing. They aren’t generally a first choice for prototype work. On the other end of the spectrum, excellent craft shops are marvelous sources of short-term solutions. In some instances, these shops may be all about handcrafted work. If you need two or more of what they make, you found the right place. (Keep in mind that you might need to sift and sort to get them to fit.)

Here’s the important lesson: A supply chain is only as good as its weakest link. Craft shops tend to have volatility in schedule, price, performance, and availability. Production shops are more reliable but less forgiving of ambiguity.

Vendor Managing. Let’s just call it hand-holding. When done correctly, it can help to convert the craft shops into something reliable. That’s important because in the manufacturing community, the ability to keep a promise is variable. Some shops are adept at shipping product on a specific date. Their internal supply chains and their production control systems result in promises well-kept. They require very little hand-holding. But often their attention-getting initial price quotes, which cover expenses integral to their services, may disqualify them from the work that is out to bid. That’s a shame because that quote covers peace of mind for their customers. All members in the supply chain team should be like this.

To focus on work-at-hand, some shops don’t bother with scheduling overhead. First come, first serve. That’s it usually. But expedites happen, don’t you know.

As a control system, the squeaky-wheel scheduling method is worth what it costs—nothing. Vendors that require extensive hand-holding in order for them to keep their promises may not invoice you very much, but they certainly are expensive in terms of your time and frustration.

Brew happy and brew often.

Gerald would love for you to send him your comments and questions. You are not alone, and the problems you face often are shared by others. Share the grief, and perhaps we will all share in the joy of finding answers. Please send your questions and comments to dand@thefabricator.com.

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