An essential part of the verification of the appearance and thinking of industrial design, as well as the verification of structural engineering design feasibility, is prototyping. Throughout this article, we would like to discuss the importance of structural feasibility prototypes for industrial design.

1. What are the specific roles of structural feasibility prototypes?

By making feasibility prototypes, we can verify design feasibility, whether there are any hidden drawbacks in the design process, and whether there is modeling error or structural design issue. All these things need to be verified through prototypes.

As part of the R&D process for new industrial product design, industrial feasibility prototypes are widely used to build a physical model that is consistent with the design in the shortest possible time. In this way, the designer can confirm the product functions and test the design, thereby reducing the development cost, shortening the development cycle, and speeding up the design approval process.

So what are the specific functions of those feasibility prototypes?

(1) Feasibility assessment of structural design 

This process involves evaluating various factors such as product size, assembly method, structural strength, clearances, and material selection. They are not identical to mass production but could be similar. For example, the raw plastics used for prototypes are solid, but they are liquid for plastic injection molding.

(2) Product functionality testing

It covers assembly tests, operation tests, drop tests, electrical tests, mainboard performance tests, etc.

(3) Pre-production cost optimization

Developing engineering prototypes is also a way to reduce costs, for example, structural parts costing (which parts are necessary and which parts can be eliminated), electrical layout optimization, assembly cost optimization, etc.

2. What is the general manufacturing process of prototypes?

(1) Preparing the design files

  • 3D files in CAD, STP, STEP, IGS, or X_T format
  • CMF file for finishing treatment
  • CDR file for silk screening LOGO or other patterns
  • BOM (Bill of Materials) stating materials and quantities of each part
  • Other special requirements

(2) Double-checking the files and getting a quotation

Ensure that the files do not need to be revised before processing with your prototyping manufacturer. Confirm the quotation before moving forward.

(3) Engineering the prototypes part by part

Classify the 3D drawings based on different processes. Some parts cannot be manufactured in one piece. They need to be disassembled into several pieces and glued together. The engineering software for CNC prototypes is MasterCAM.

(4) Manufacturing

The most widely-applied prototyping method is CNC machining. 3D printing and vacuum casting are also suitable choices. Materials, quantities, and tolerances all play a role. Should they be plastic prototypes or in other materials? How many do you need? What are the tolerances?

(5) Manual check and repair if necessary

Clean up the parts and get rid of all the unwanted burrs. Also, the technicians need to check the 3D files to see if they are processed as required. In that case, the engineering prototypes must be machined a second time to make up. Sometimes, the makeup work can be done manually.

(6) Finishing treatment

Finishing the parts based on CMF files. For feasibility prototypes, usually, they don’t have to be well finished if you don’t want to check the appearances at the same time. Finishing treatments differ a little bit for plastic prototypes and metal prototypes.

(7) Assembly and quality check

After all the finishing is done, assemble all the parts step by step. When the assembly is completed, it is necessary to check whether the engineering prototype as a whole meets the design requirements.

In terms of structures, we need to check whether the parts can be put together. We also need to check whether there are any problems such as improper assembly, interference, screw holes not processed in place, and other processing defects.

3. What else work needs to be done after prototyping and before mass production?

As rapid prototyping is different from mass production molding, there are still many disadvantages that will impact the product design. When you get the prototypes, you still have check work to do, including a processing check and a design check.

(1) Processing check

A) If you don’t ask the prototyping manufacturer to assemble for you, you should check whether all parts can be assembled, whether there is interference ( caused by manufacturing or design), and whether the parts are consistent with 3D drawings.

B) You also need to check the measurements to see if they are within reasonable tolerances. Usually, the tolerance falls in the range of +/- 0.5 ~ +/- 1.5 mm. The larger the item, the larger the tolerance. Plastic prototypes enjoy higher tolerances. But metal ones don’t. So you need to clearly indicate the specific tolerances of key parts.

C) Check if there are any missing parts. Then you won’t have any problems when assembling.

(2) Design check

A) Inspect the prototype for structural defects after assembly, and determine whether they were caused by the prototype's processing or structural design.

A plastic prototype might have a snap force of 0.4, but the actual assembly would be loose. Then we need to find out if the prototype is not processed properly. This causes the snap volume to be reduced, or the snap arm is too long and forceless which causes it to be very loose.

B) You need to test the material thickness, deformation, and strength of metal components. If the deformation of the metal parts causes an assembly problem, you need to check whether it is because the design doesn't consider the possible processing deformation, or it is caused by manufacturing issues.