Designers always want to save time and money during prototyping, but
“cheapest and fastest” is usually not the best option. The top
prototyping methods—stereolithography (SLA), selective laser sintering
(SLS), urethane cast, soft tooling, and hard tooling—all have their
advantages and disadvantages. What must be considered is how the
prototype will be used and what the production goals are, especially if
you are making a tight-tolerance part that’s critical to the function of
a product or system or if it is something that requires a plastic overmolding.
SLA/SLS
These additive manufacturing technologies are ideal for rapid prototyping. Guided by a CAD pattern, SLA uses an ultraviolet laser to build a solid part by solidifying and accreting individual layers of photopolymer resin. Although SLA is relatively fast, there are size limitations and photo-curable resins can be expensive. SLS is similar to SLA except that a carbon-dioxide laser fuses together thin layers of powdered metal, plastic, glass, or ceramic to construct a solid product. Compared to SLA, SLS can make prototypes from more materials that may have properties closer to production-intent materials. Even though materials options have increased over the years, SLA and SLS are not yet production intent.
These additive manufacturing technologies are ideal for rapid prototyping. Guided by a CAD pattern, SLA uses an ultraviolet laser to build a solid part by solidifying and accreting individual layers of photopolymer resin. Although SLA is relatively fast, there are size limitations and photo-curable resins can be expensive. SLS is similar to SLA except that a carbon-dioxide laser fuses together thin layers of powdered metal, plastic, glass, or ceramic to construct a solid product. Compared to SLA, SLS can make prototypes from more materials that may have properties closer to production-intent materials. Even though materials options have increased over the years, SLA and SLS are not yet production intent.
Urethane Cast/Mold
This low-volume production method utilizes polyurethane plastic materials to produce prototypes that can be finished to look like hard-tooled plastic parts. However, material choices are limited and may not deliver the same qualities that preferred production plastics can. Urethane cast/mold can be a cost-effective method of prototyping if there is a need for a higher quantity of parts at the fitment or proof-of-concept stage. Overall the process is fairly limited and becoming less common in the industry.
This low-volume production method utilizes polyurethane plastic materials to produce prototypes that can be finished to look like hard-tooled plastic parts. However, material choices are limited and may not deliver the same qualities that preferred production plastics can. Urethane cast/mold can be a cost-effective method of prototyping if there is a need for a higher quantity of parts at the fitment or proof-of-concept stage. Overall the process is fairly limited and becoming less common in the industry.
Soft Tooling
This process provides relatively cheap tooling, a high number of parts, and may also allow for use of the intended production material. Soft tooling is usually built with aluminum cores and cavities and samples can be turned around in a few weeks. This may be an option for early prototype builds if the parts are simple, tolerances are loose, and function and fitment are not critical requirements.
This process provides relatively cheap tooling, a high number of parts, and may also allow for use of the intended production material. Soft tooling is usually built with aluminum cores and cavities and samples can be turned around in a few weeks. This may be an option for early prototype builds if the parts are simple, tolerances are loose, and function and fitment are not critical requirements.
Hard Tooling
For engineered parts with tight tolerances, testing requirements, and an intention for functional use, hard tooling is usually the best option. The up-front cost is more expensive and the lead time is longer; however, hard tooling will likely save both time and money down the road. It will guarantee the ability to use production-intent resin and can accommodate design and dimensional changes after the parts have been sampled. Hard tooling also provides the opportunity for process development and verification early in the program timeline. It’s also a good choice for supplying several hundred thousand parts, bridging the gap from prototype to production.
For engineered parts with tight tolerances, testing requirements, and an intention for functional use, hard tooling is usually the best option. The up-front cost is more expensive and the lead time is longer; however, hard tooling will likely save both time and money down the road. It will guarantee the ability to use production-intent resin and can accommodate design and dimensional changes after the parts have been sampled. Hard tooling also provides the opportunity for process development and verification early in the program timeline. It’s also a good choice for supplying several hundred thousand parts, bridging the gap from prototype to production.
Understanding what you need is important when considering which
prototyping method to select. Cutting costs during the development stage
by opting for the least expensive prototyping option generally doesn’t
save the money over the long term—be sure to evaluate lifecycle costs as
well. (Source: Medical Injection Molding by Kaysun)
