“Design changes.” Those two simple words can cause even the most experienced parts manufacturer to panic.
After all, design changes are notorious for adding time, headaches, and unplanned dollars to a project. They’ve also been known to sabotage solid business relationships. Yet, they’re inevitable in manufacturing; as much as we try, they come with the territory.
Success is determined by how a design change is handled.
When it comes to machined parts, designing with an eye on the machining process can generate large and long-term savings in part costs. Taking time to consciously think about how a part will be machined can increase a machinist’s performance and decrease the overall budget.
As far as changes go, it’s natural (and correct) to assume that making design changes to a part currently in production is more complex than making changes to a part still in the design phase. Some factors that require attention when addressing a change to a part currently in production include current inventory, schedules, and purchase orders to vendors.
This article covers a handful of simple rules for addressing design changes more successfully. After you review these and devote time to implementing them, you’ll be less likely to break out in a cold sweat when someone mentions “design changes.”
1. Ensure Your Partner Has Engineering Expertise
As often as you’ve heard this, there’s really no substitute for experience. A team that works on hundreds of design changes each year and has a customer base of old and new product development is what you’re looking for.
Extremely talented manufacturing engineers can quickly assist with design changes as well as rapid prototype services for cast and machine tools. Quickly generating prototype parts allows their performance to be tested before they’re manufactured in large quantities.
As stated earlier, designing with an eye on machining is important. Yet, just as critical is designing parts that are easy to hold. Proper workholding reduces the possibility for error and ensures parts are machined to the proper specifications.
Approaching design with years of experience and knowledge distinguishes a machining partner and keeps customers coming back.
2. Demand Detailed Project Management
Project management can also set a machine shop apart from others. First, having an in-house team — manufacturing engineers and full-time fixture building machinists — means you’ll get dedicated performance and experience peace of mind.
When parts are in the design phase, the team works with the customer to provide print feedback for machinability, geometric dimensioning and tolerancing (GD&T), and guidance so the part is as cost-effective as it can be. Customers also get valuable input on machining designs prior to launch, including design review and advanced product quality planning (APQP) meetings.
Second, consider if a shop has in-house experts on castings who develop multiple foundry partnerships. If they regularly collaborate to tackle design changes, you can rest assured that changes are handled quickly and successfully.
Third, solid foundry partnerships are magnified when the right tools are available to deliver design changes swiftly. Proper machine tooling, machining centers, and programming capabilities are needed when manufacturing machined castings. For instance, with state-of-the-art, 3-D CAD fixture expertise (and a well-thought-out plan), the expectation is for design changes to happen efficiently.
3. Consider the Importance of Part Tolerances
Quality is also a major part of design changes. Think about it: just about anything can be machined once. But can hundreds (or thousands) of parts be run with the same consistency? Again, it takes tools and expertise to get the job done right the first time and every time.
Part tolerance is one obvious way to measure quality. Tolerance is a dimensional range that’s deemed acceptable by the designer and is based on the part’s function, fit, and form. Not meeting tolerance can result in more foundry or machine scrap, a product not functioning properly, tooling rework, extra machining, and/or warranty issues from a customer.
Design changes require as much attention to tolerances as any other project. After all, exact means exact, no matter what the project. However, it’s important to remember that a tighter tolerance can result in additional cost, additional fixturing, or longer cycle times because slowing down the machine may be the only way to achieve some tight tolerances. To keep costs down, designers should only apply tight tolerances to critical areas.
4. Dominate on Drawings
Drawings from customers have a huge influence on a shop’s success. To produce the best and most cost-effective part, it's important to spend time on drawings. Great prints produce great parts.
This holds true for design changes. Because a print is the primary direction to a machinist, it needs to be clear and legible. Machine shops evaluate a print to their best abilities, planning all steps based on what is available. That drawing holds the key to avoiding mistakes and saving money (which are likely top-of-mind during design changes).
5. Keep Things Professional
This final point isn’t as process-related as the other four, but it’s important. One reason why the phrase “design changes” strikes fear in the hearts of otherwise strong and confident machinists is because of their past experiences. Change projects are often presented negatively and loaded with emotional baggage. Remember, meeting tight tolerances is a challenging art, and mistakes are bound to happen.
So, be professional and get the best from a machine shop by following this simple checklist:
[ ] Communicate clearly and often; confront problems and resolve issues fairly
[ ] Consult on design changes; many machinists have years of experience and training
[ ] Be financially aware; pay bills on time, don’t use the shop as a free quoting service, and don’t beat them up on part costs
[ ] Treat the shop as a team member; dedication and extra effort result from mutual respect
That list may not be “design change” specific, but it seems appropriate for the topic. Design changes are no fun for anyone, but they happen … and people get emotional.
If reading about what it takes to execute successful design changes has piqued your interest in quality machine shops, check out this post, 6 Questions to Find a Great CNC Machining Partner. Uncover the right capabilities, the proper certifications, and how the right shop goes the extra mile when you need it most.