| Rapid prototyping (RP) and rapid tooling (RT) | | | | you need to run these molds in a press with a |
| technologies, processes and developments have | | | | processor at the machine to manually disassemble |
| changed over the years, but there is one thing | | | | all the pickouts. If you only run open and close |
| that has remained constant: the challenge to get | | | | tools, these molds can run unattended. This is the |
| functional prototypes and a method to obtain | | | | reason many people did not offer making rapid |
| low-volume production parts fast, without | | | | tools with undercuts. With newly developed |
| breaking the bank. | | | | moldmaking software and a better awareness of |
| The race in rapid tooling to get either functional | | | | cycling at the press, molds are being shot |
| prototypes or low-volume production parts has | | | | everyday capturing undercuts with hand pickouts |
| created many methods of rapid tooling, which | | | | and manual slides. |
| have worked well and not so well. The downside | | | | 3. You can shoot clear parts in a rapid tool. |
| to each of these methods has been the | | | | Aluminum molds can be polished and/or textured |
| consistency and the lack of broad use from | | | | to shoot clear or transparent parts. This is a |
| application to application. | | | | secondary procedure, the same as you would |
| Due to thick wall sections and dimensional warping, | | | | have in a production mold. The aluminum can be |
| the mold was modified to core out the plastic | | | | polished up to an A-2 finish. A-3 is more typical |
| part. Images courtesy of Vista Technologies. | | | | and lasts longer in production runs. Depending on |
| Old school rapid tooling was very niche-specific. | | | | the material being run, the A-2 finish might see |
| One method would work well for open and closed | | | | more wear and dull the finish over time. |
| molds, while another method was better for | | | | Polycarbonates and acrylics are the most |
| running 20,000 parts. Previous methods that were | | | | commonly run materials to get a clear plastic part. |
| used include Direct Aim tooling, epoxy tooling, SLS | | | | Many materials have been runwith a custom |
| Laserform and Keltool. These methods had their | | | | transparent tint from Udel to polycarbonate. |
| strengths, but carried stronger weaknesses--such | | | | 4. You can shoot high volumes in a rapid tool. |
| as poor tolerance, tool life and narrow material | | | | High volume is a relative term, so let's define it as |
| selections that you could inject under pressure. | | | | 50,000 parts. Obviously, a lot of projects need |
| Since people tried to use these niche methods of | | | | runs larger, but 50,000 is quite a contrast |
| RT across a broad base of projects and had | | | | compared to the 500 quantities that were |
| more failures than successes, people started to | | | | rumored off rapid tooling. These volumes are |
| label all methods of RT as very limited. Once | | | | limited to material and part design, but many |
| people were exposed to a less than successful | | | | molds have shot abrasive materials with multiple |
| RT project, these labels became gospel. | | | | pickouts in the tens of thousands. |
| However, times have changed, and it is time to | | | | Again, processing at the press and having the |
| dispel these rapid tooling myths, which have | | | | need for speed, but not the greed for speed are |
| plagued the RT industry and prevented many | | | | the important variables in running larger runs. If |
| people and customers from successfully benefiting | | | | you are trying to match production mold cycle |
| from the technology. It is important that people | | | | times with aluminum, you will eventually run into |
| are exposed to the truth about RT. Here are the | | | | issues. If you use common sense and finesse, |
| six main myths of RT that have plagued the | | | | you will capture benefits of higher volumes from |
| industry. | | | | your aluminum tool. |
| You cannot make tool modifications in a rapid tool. | | | | 5. You can shoot large parts in a rapid tool. |
| You cannot capture undercuts in a rapid tool. | | | | Again, this is a relative term. Large parts for a |
| You cannot shoot clear parts in a rapid tool. | | | | medical company may not be considered large for |
| You cannot shoot high volumes in a rapid tool. | | | | an automotive company. The point in this myth |
| You cannot shoot large parts in a rapid tool. | | | | being dispelled is that aluminum tools are not |
| You cannot shoot most engineering grade | | | | limited to a six-inch cube. |
| materials in a rapid tool. | | | | On average, many parts do fit into this frame. |
| Before the myths are dispelled, we should first | | | | There are still many parts that exceed the 18" |
| describe what method of rapid tooling we are | | | | x10" x6" envelope that are being made in an |
| discussing. This method is using 7075-T6 aluminum | | | | aluminum rapid tool. This is a very common |
| rapid tooling that has been milled using high-speed | | | | practice that allows for great price reductions and |
| milling (30,000-42,000 rpms). Delivery of these | | | | helps in reducing leadtimes. |
| molds varies from vendor, but in general you can | | | | 6. You can shoot most engineering grade |
| get a consistent delivery in two to three weeks. | | | | materials in a rapid tool. |
| Six Truths of Rapid Tooling | | | | Using aluminum tools allows you to sample the |
| 1. You can make tool modifications in a rapid tool. | | | | same materials as you would in a production mold. |
| Aluminum tools can be welded, inserted and | | | | Glass-filled Nylon, Ultem, Peek and PVC have all |
| re-machined. In fact, for every 10 molds made, | | | | been run in aluminum tools. These molds can be |
| six get modified after the first sampling due to | | | | cooled or heated to meet the processing |
| part redesign. This has been a great advantage | | | | requirements. The day of only shooting ABS or |
| because now people can spend less time and | | | | Santoprene is over. Filled materials, exotic |
| money making tool modifications on a prototype | | | | materials and waxes are all being sampled in |
| mold rather than spending even more time and | | | | aluminum tools everyday to get functional |
| money in changing the production mold. | | | | prototypes or low-volume production parts. |
| Changes in molds can vary from changing part | | | | These are the six main myths that have held |
| features, hole sizes, eliminating sink and even | | | | aluminum tooling back from helping to jumpstart |
| changing gate locations. Most of these changes | | | | projects into a smoother transition in production. |
| occur after first parts are shot, assembled and | | | | Other myths that should not be ignored are the |
| tested. With spec materials fit and function are | | | | ability to also do insert molding, over molding and |
| now easy to test under real elements. If | | | | making family tools. Also, tolerance in a rapid tool |
| adjustments are required the tool is then modified | | | | does compare to a production tool. This has been |
| to meet the new part design. | | | | proven time and time again from first runs to final |
| 2. You can capture undercuts in a rapid tool. | | | | runs. |
| Undercuts, side actions or side pulls can all be | | | | In conclusion, many projects have been brought |
| designed to be captured in aluminum tools. These | | | | to production with questions unanswered, over |
| features can be captured by hand pick-outs and | | | | budget and with forecasts and timelines being |
| manual slides. By making these pick-outs manual, it | | | | missed that could have all been prevented by |
| keeps cost and delivery to a minimum. This is | | | | using rapid tooling. The next time you have a |
| advantageous to the customer, but not the | | | | need for 50 to 50,000 parts from a spec |
| supplier because it adds complexity to the mold | | | | material, do not let the myths of rapid tooling lead |
| design, the machining and the mold assembly. | | | | you astray. |
| The biggest disadvantage to the supplier is that | | | | |