Being second to market with a new product gives faster competitors the opportunity to dominate. There’s no room for mistakes or delays when moving from prototype to volume production. Procuring and proving-out mold tools can delay the start of production by weeks or even months. It seems logical to bring forward tooling orders, but with high costs and uncertain demand, managers are often reluctant to take that risk.
Bridge tooling is the answer. Bridge tooling spans the gulf between prototype and full production tooling. It produces actual, customer-ready parts rather than prototype representations, ensuring functional and aesthetic requirements are met.
Bridge tooling is less costly than the full production equivalent, reducing the financial risk in launching a new product. It also takes less time to make. The tradeoffs are tooling longevity and possibly also piece part production rate.
A Bridge Tooling Primer
The main issue with production tooling is that it’s made from hard tool steel. This provides a lifetime of millions of pieces but requires slow and expensive machining and finishing operations
Second, to maximize production rate, production tooling often designed with multiple cavities. If the anticipated sales ramp up slower than expected, or don’t materialize at all, the manufacturer is faced with building inventory or adapting the processes for lower volumes.
Bridge tooling avoids both these complications.
There are several ways to make bridge tooling. The most straightforward is to use aluminum. Aluminum tools can be machined and finished in far less time than steel, are more easily modified if needed, and have better thermal conductivity. This last point has implications for molding cycle time. The 7000 grades of aluminum in particular polish well for a good surface finish.
A second way of reducing time and cost is machining fewer cavities. Once initial pre-launch quantities are in inventory, production is usually low until the product becomes established and demand grows. Fewer cavities also shrinks overall tool size, allowing for the use of lower-volume production equipment.
Third, consider modular tooling. This approach is especially useful when making a family of parts. Rather than making a number of similar tools, make one and use inserts to change characteristics like length or number of holes.
Moving on from Prototype Tooling
Some manufacturers try using prototype tooling for production parts. This almost always fails, for one or more of these reasons:
- Tooling isn’t suitable for the production materials.
- Tooling can’t produce the appearance needed.
- Tooling can’t achieve the tolerances needed, forcing expensive hand finishing.
- Tooling is incompatible with the production processes.
In addition, there’s a missed opportunity. Bridge tooling lets the manufacturer analyze and improve the production process. In many cases, heat flows and cooling rates will differ from what was expected, resulting in unexpected shrinkage or warping. Bridge tooling highlights such issues while there’s still time to make design or tooling changes.
Managing the Transition to Bridge Tooling with Care
Moving from prototype to bridge tooling presents several challenges. Materials may be different, the focus on piece costs and volumes increases, and there are often legislative or market requirements to meet. Here are six imain ssues to consider:
- Tool longevity. Well-made bridge tooling lasts thousands of cycles. (Some authorities report as many as 200,000.) Given the anticipated sales rate, consider how much time this provides before steel tooling is needed.
- Prototype parts are often produced in a different material than the final production pieces. If switching material, verify that part and tool designs have been reviewed and adjusted to suit.
- Cycle time/production rate. Production rate takes on greater significance during initial product start-up. Aluminum tooling doesn’t retain heat like steel, so mold tools are quicker to reach temperature and allow faster cooling prior to ejection or release. This may allow a higher output rate, and as discussed earlier, the number of cavities will also impact process economics.
- Secondary processes. Parts often leave prototype tooling in an unfinished state. Hand trimming is the norm to ensure parts assemble correctly and give the appearance needed. These secondary steps add cost and time, so bridge tooling should be designed to eliminate as much of this work as possible. For example, more work may be needed to reduce and distribute flash.
- Markings and serialization. In many industries, parts being incorporated into saleable products must have appropriate identifications and possibly also serial numbers. This is usually omitted at prototyping but needs to be accounted for in bridge tooling.
- Design changes. While aluminum tooling is modified more easily than steel, it’s preferable to freeze designs before actually cutting metal.
Reducing Risk, Accelerating Launch
Bridge tooling reduces both time-to-market and the financial risk of procuring steel tools for high-volume production. Tools used for prototype production are rarely suitable for bringing a new product to market, although they may inform the tool design decisions. Bridge tooling trades life for lower cost and faster delivery. For many manufacturers, it’s a cost-effective approach, providing the needs of production parts are considered carefully.
If you need help making the transition from prototype to bridge tooling, or simply have questions about the process, please feel free to contact us here at 3-Dimensional Services Group.