Designing a new part is one thing. Manufacturing it is a different story.
Talk with any customer of a CNC machine shop, and you’ll no-doubt hear an example of their part design being altered, refined, and/or improved thanks to a CNC manufacturing engineer. Of all the CNC engineering services provided by a machine shop, having an influence on the design itself may not be what you think of first.
Yet, without that insight, there’s no way to determine a part’s design for manufacturability (DFM). And, when you consider all the reasons why a part needs to be more manufacturable — to handle high volume production, to maintain high quality, to make the process easy and, the big one: to keep costs low — it’s clear that a CNC engineer’s modification of a part design is critical.
Let’s explore how that’s done and why it’s so valuable.
Specialization = Efficiency
Fixture design. Fixture building. Tooling. Programming. Processing. And more! There are so many CNC engineering services performed by CNC engineers. In small CNC shops, one or two engineers are forced to multitask, handling all of these services and having to stop and refocus on the most urgent need.
While it may be beneficial to have engineers with well-rounded skill sets, that’s not exactly efficient. Within the most top-end shops, no single engineer has all of these responsibilities; engineers specialize in one service. This specialization allows engineers to do what they do best all of the time, continually sharpen that skill, and improve the quality of all projects in that shop (more on quality later).
An Example of CNC Engineers’ Influence on Part Manufacturability
Here’s an example of the depth of influence that CNC engineers can have on a part’s long-term success. A manufacturer of heavy equipment has a design for an aluminum transmission housing. Perhaps before the project is even awarded to a source for CNC machining, the part design may be evaluated by:
The CNC Machine Shop: the sales and engineering team leader (quotes the part, runs cycle times); the fixture design engineer (considers machinability and clamping; checks the prints for errors); and the tooling engineer (tooling available (common tooling possible); a quality engineer may also be included, depending on the part’s complexity
The Foundry: usually selected by the CNC shop, the foundry representative discusses castability, asks relevant questions, and inputs ideas
The Customer: part designer (typically a mechanical design engineer who knows the part inside and out); the purchasing manager and/or purchasing buyer; and the quality engineer (makes sure processes are effective, efficient, and safe)
Having all of these people in the same room at the same time allows the team to walk through the manufacturing plan. Clamping, machining, and tooling are all planned out so there are no surprises and the result is a smooth PPAP process.
Diving a bit deeper, the CNC machine shop reviews the prints, all specs, the material, and determines any efficiencies that may be gained by modifying the design. For instance, what is spec’d may be altered to use common tooling, which saves money and time. Or, the number of holes may be reduced (or all can be uniform) so an extra tool isn’t required.
Another topic for discussion is tolerance. The aluminum transmission housing design specs call for .05mm (or 50 microns) when an acceptable tolerance would be .13mm. That one simple change could save over $2.00 per piece in tool costs, extra passes, etc. Even on a part that may cost hundreds of dollars, the savings are significant when machining thousands of them each year.
Now is a good time to cover the importance of casting. Including the foundry early can make a huge difference in part manufacturability. This initial meeting is the time for the foundry to input ideas and help make the part manufacturable from the very beginning (we all know the challenge of changing a design after everyone has signed off on it.) For instance, adding a rib along the side of the aluminum transmission housing helps feed the casting, making the part more castable.
3 Key Ways CNC Engineers Impact Part Design
Engineers in a CNC machine shop are not part designers. That’s the responsibility of the customer. That said, engineers do heavily influence how a part will perform in these three ways:
- Simplifying — Evaluate overall part design, look for common-sized hole length and common fastener sizes, find opportunities for fewer tool changes on the spindle (saving time and money)
- Optimizing — Put clamp locators on the part to optimize clamping, use surface finish callouts, uncover ways to improve the manufacturing process
- Refining the Product Design — Add feeding ribs to prevent defects and make machining easier, adjust geometry (radius and draft, for instance) to make it the most castable part it can be.
The 1-2 Punch of Experience and Technology
There’s no substitute for experience. Similarly, there may be no substitute for completing a task; only the latest technology can accomplish it. Engineers rely on both experience and technology (usually in equal amounts) to be successful.
I can’t say with 100 percent certainty, but I don’t think there are many books or YouTube videos on designing custom CNC fixtures for parts. It’s really a skill passed down from the expert to the novice, with experience being the best teacher.
A complement to experience, the ability to stay on the edge of technology — from hydraulics to clamping to sensoring — provides capabilities that cannot be matched any other way.
Fair Price and Few Headaches
Proper design for manufacturability upfront is the roadmap to a part’s success and longevity. It emphasizes early team involvement (especially for complex parts), drives maximum efficiency and cost savings, and creates a smooth, repeatable process. When a CNC machining source can reduce a customer’s stress level, it’s a win.
It’s also important to remember that you get what you pay for. Experienced Purchasing Managers expect modern CNC machine shops to have engineering experts on-staff, and they’re willing to pay for that expertise.
Stecker Machine has over a dozen engineers on staff. Engineers are focused on their area: fixture design, tooling, programming, processes, packaging, and quality. That’s a LOT for a shop of our size.
Ready to learn more about how high-end CNC machine engineering drives part manufacturability? Read this. Our CNC tooling guide shares the best process for approaching CNC tooling needs and includes some real-life examples of tooling solutions. Click the link below to get your copy!
Want to contact Stecker now? Call 920-726-4526.