Various plastic prototyping techniques are available to manufacture plastic parts quickly. Plastic prototypes are required for Initial product design verification and validation. Prototyping helps in reducing overall product development time and launch products faster in the market. This article covers various plastic prototyping techniques their advantages, applications and limitations.
Factors affecting the Selection of Plastic Prototyping Technique
Following factors affect the selection of best plastic prototyping technique for required application.
- Product Functional and Aesthetic Requirements
- Cost Constraints
- Lead Time
- Required Quantities
Plastic Rapid Prototyping Techniques
Various plastic prototyping techniques are available to manufacture plastic parts quickly. Each process has their own advantage and limitations
Additive Manufacturing / 3D Printing
Additive manufacturing / 3D printing is one of the fastest way of plastic prototyping. In 3D printing, plastic prototypes are created by adding successive layers of material. Each of these layers can be seen as a thinly sliced horizontal cross-section of the final part.
Following 3D printing technologies are available for plastic prototyping. Each technique has their own strengths and weaknesses.
- FDM (Fused Deposition Modelling)
- SLA (Stereolithographiy)
- DLP (Digital Light Processing)
- (SLS) Selective Laser Sintering
- Material Jetting (PolyJet and MultiJet Printing)
- Metal Printing (Selective Laser Melting and Electron Beam Melting)
|Material Options||3D printing materials are available in various grades that are similar to commercial grade plastic. Even metals such as aluminum can also be 3D printed.|
|Engineering Tolerance||Depending on 3D printer, part geometry and material, tolerance in the range of 50 to 150 microns can be achieved.|
|Cost and Lead time||Cost and lead time for 3D printed prototypes very less compared to cnc machining prototypes. You can get the 3D printed prototypes within hours.|
|Part Quality||Very good quality prototypes can be manufactured. But manufacturing cost is very high.|
|Ideal Quantities||1 to 20 Units|
CNC machining is the best way to create functional functional plastic prototypes. It is a subtractive manufacturing process, where material is removed from solid block by using a variety of precision cutting tools.
Post processing operations such as buffing, sand blasting, plating, painting or screen printing are required to achieve required part finish on plastic prototypes.
|Material Options||ABS, PC, ABS+PC, HDPE, Nylon and Hard PVC etc. solid blocks are available for plastic part prototyping.|
|Engineering Tolerance||General tolerances ” ISO-2768 m” is applicable for cnc machined plastic prototypes.|
|Cost and Lead time||Manufacturing cost is very high. Therefore they are recommended for small quantities.|
|Part Quality||CNC machined prototypes are functional and identical to injection molded parts. Various validation tests can be performed on CNC machined plastic prototypes.|
|Ideal Quantities||1 to 20 Units|
Vacuum Casting / Silicon Rubber Mold
Polyurethane vacuum casting is used for manufacturing high quality and low volumes prototypes using silicone molds. Masterpiece (generally 3D printed part) is required to develop Silicone Mould.
For plastic prototyping, silicone mold is filled with two part polyurethane resin inside vacuum chamber and then processed in a heat chamber at controlled temperature.
|Material Options||Commercial grade injection molding thermoplastics equivalent materials are available.|
|Engineering Tolerance||Tight tolerance are very difficult to achieve in vacuum casting prototypes. Depending on feature complexity, Tolerance in the range of 100 to 150 microns can be achieved.|
|Cost and Lead time||Silicon molding is more economical if manufactured in the multiples of 10 to 15.|
|Part Quality||Silicon molded plastic prototypes are functionally and aesthetically more close to injection molded parts.|
|Ideal Quantities||10 to 100 Units|
Quick turn injection molds is a good choice for moderate prototype quantities. Sometimes they are also known as intermediate tools.
Following technologies are used for rapid tooling:
- 3D Printed Plastic injection molds.
- Machined Aluminum injection molds.
- 3D printed metal injection molds.
|Material Options||Almost all thermoplastic materials can be used.|
|Engineering Tolerance||Tight tolerances can be achieved using rapid tooling.|
|Cost and Lead time||Compared to silicon molding tool, initial Investment cost for rapid tools is very high. Rapid tooling lead time is approximate 2 to 3 weeks.|
|Part Quality||Rapid tooling prototypes are identical to injection molded parts. The only difference between rapid tool and final tool is the material used for tooling.|
|Ideal Quantities||100 to 5000 Units (Depends on Material Used)|
|Properties||3D Printing||CNC Machining||Vacuum Casting||Rapid Tooling|
|Tooling Cost||NA||NA||Very Low||High|
|Unit Part Cost||Moderate||Very High||High||Low|
|Form and Fit||Moderate||Good||Good (not better than CNC)||Excellent|
|Lead Time||Low (hours to days)||Moderate (3 to 7 days)||High (min 7 days)||Very high|
|Quantities||1 to 50||1 to 10||10 to 100||100 to 2000|
To sum up, Rapid prototyping is one of the best way to ensure designed product is meeting required expectations. Various prototyping techniques are available. But FDM 3D printing is extensively used. FDM printers starts from $300. Refer summary table for comparison between various technologies. We suggest you to read this article to know the factors affecting injection mold cost.
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