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Consider a Multi-Part Design with Mechanical Assembly For Your Prototype Model

Rome wasn’t built in a day, right? It all came together a bit at a time.

Large, bulky parts are a lot like great cities. It’s often best to design them in multiple components instead of trying to machine just one complex part. 

Designing an entire prototype model as one part may seem like the fastest, cheapest, and easiest solution. But the reality is you may be paying up for an enormous piece of material that takes a long time to machine. 

Instead, breaking your model down into smaller components to be assembled can actually reduce machine time and material costs.

If you’re still feeling skeptical about designing one part as multiple components, you might be falling for some common CNC machining myths. 

Let’s dispel those myths right now!

Myth 1: I’ll spend less time and money on prototype machining if I use one piece of material.

There’s a common misconception that when you need a part quickly, you should make it out of a single piece of material.

 But purchasing and shipping a large piece of material is typically more expensive than purchasing and shipping multiple smaller pieces. Then there’s all the excess waste that results from machining a bigger piece of material. More often than not, customers wind up paying for a significant amount of material they don’t need.

Multi-part prototype design

Not only does the material itself cost more, but having to remove excess material during machining increases run times as well. Prototype models with features like long standing components also require the use of long tools that have to move slowly to avoid chatter. Plus, large parts machined from one piece of material are far more likely to warp.

The bottom line is that increased cycle time and material use result in increased cost and lead time. Machining multiple components and adding fasteners is often faster and less expensive than machining a part out of one piece of material.

Myth 2: Single-part prototypes are more precise and cosmetically pleasing.

You don’t need a single-part prototype model to achieve tight tolerances and a beautiful cosmetic appearance. 

If you’re concerned about the cosmetic appearance, we can make your fasteners blend in so that they can hardly be seen. Depending on size, we often suggest using two location pins and 1-4 stainless steel thread fasteners that are corrosion-resistant and prevent oxidation. We then machine the material to appear seamless so the fasteners are nearly invisible. 

If you’re concerned about precision and accuracy, you might be surprised to learn that you can actually get a more precise model from an assembly with added fasteners. We can add fasteners into your prototype model for you; all that’s required is your review and authorization.

Machining a large part where long tools are required introduces inherent stress that makes it more challenging to maintain very tight tolerances. But with mechanical assembly, we can machine separate, roughed out components, assemble them, then machine them all as one piece to achieve a consistent finish and maintain your tolerance requirements. We typically recommend this method for single-sided parts or models that are mainly machined from one side.

Myth 3: The design needs to be the same for prototyping and production. 

If you’re planning to use injection molding or die casting for volume production, it makes sense to design a single part instead of an assembly. Tooling is expensive, so you don’t want to have to pay for custom tooling for multiple parts. 

But when you’re making a proof of concept prototype model to test form, function, fit, and finish, you can often get what you need for less money with a multi-part assembly. So don’t be afraid to adapt your volume production design to optimize for prototyping. 
Need help determining if your prototype model would benefit from mechanical assembly? Request a quote from KAD today!