Model Patterns
Model Patterns Reduces Lead Times 
and Costs with the 3D Keltool® Process

A steady decline in the availability of skilled toolmakers, coupled with increasing competition globally, led UK-based Model Patterns to investigate alternative methods of producing high quality injection mold tools—faster and at lower cost— than traditional techniques.

Model Patterns found the solution in the 3D Keltool process from 3D Systems, which enables the company to produce complex multi-impression tools for its varied customer base extremely quickly and efficiently.

In fact, since becoming one of the first UK companies to actively utilize the 3D Keltool process, Model Patterns is confident that it can provide its customers a reduction in lead times of between 20% - 50%, as well as cost savings in the realm of 20%.

"Over the last decade it has become extremely difficult to find skilled toolmakers," explained Richard Reano, proprietor of Model Patterns. "As a result, it was becoming increasingly hard to grow the business in this area, even though there is a continuing growth in demand for quality mold tools. I very quickly realized that if the skilled personnel weren’t available, then I would have to look to technology to survive and prosper."

Model Patterns is an established company, which provides rapid prototyping, pattern making, tool making and injection molding services to customers across a diverse range of industries— from automotive and electronics, to consumer and telecommunications.

One of the key factors to success is the ability to provide a service, which enables the customer to get its product to market quicker. It is this factor, combined with the reduced cost of a tool produced using the 3D Keltool process, that has enabled Model Patterns to remain competitive and maintain business growth.

How It Works
The 3D Keltool process starts with the production of an accurate master pattern, which Model Patterns produces on their SLA machine. Typically, the customer supplies Model Patterns with data in the form of a computer-aided design (CAD) file. From there, a physical model is produced on the SLA machine, as a means of qualifying both the accuracy and quality of the data. The resulting model is a valuable tool in gaining initial approval from the customer, prior to proceeding further in the process.

Once acceptance of the initial prototype has been established, Model Patterns typically creates new and precise geometry for the job, to ensure optimum accuracy of the master pattern. The data is downloaded in STL format from the company’s NC Graphics CAD/CAM system to the SLA machine.

"The process provides us with both the flexibility and the control to produce complex, highly accurate, high-performance production tooling at a fraction of the cost and often in half the time."
                                                          Richard Reano, Model Patterns

The master pattern is then placed into a suspended mold box into which room temperature vulcanization (RTV) rubber is poured to form the mold. Typically, curing time for the rubber takes approximately twelve hours. Then the master pattern is removed,
leaving a reverse mold into which a mixture of powdered A6 tool steel, tungsten carbide and a polymer binder is poured.

This mixture is left to cure for approximately 18 hours, and the resultant ‘green tool’ is removed from the mold and sintered in a hydrogen-reduction furnace. During this process, the polymer binding material is burned off, creating a ‘brown part’ that is A6 steel /tungsten carbide and void (air).

The final step in the process is to infiltrate the open spaces in the sintered part with copper. The resulting part is a highly accurate, production steel insert comprised of 70% A6 tool steel and tungsten carbide, and 30% copper.

The A6 tool steel gives excellent wear resistance and low distortion, while the tungsten carbide provides superior hardness and durability. Furthermore, the copper gives added strength and improved thermal conductivity. The latter being particularly important in injection molding operations, as it dissipates heat very quickly, enabling simplification of the mold tool cooling system and enhancing cycle times.

At present, Model Patterns takes the process to the stage of producing the RTV mold, then ships the mold to a 3D Keltool licensee in the United States for producing the inserts. Typically, the inserts are manufactured and returned to Model Patterns in two to three weeks, including shipping, with the company then fitting them to a standard bolster or injection tool insert.

Bottom-Line Results
In a recent project, Model Patterns was able to cut the lead time on a 36 impression injection mold tool for bottle caps, from 26 weeks to just 14 weeks. "Typically, the 3D Keltool process is best suited to complex multi-impression tools. This is where it gives real benefits in time and cost savings, by eliminating the requirement for many hours of costly CNC machining and spark eroding (EDM)," commented Reano.

"To summarize, the process provides us with both the flexibility and the control to produce complex, highly accurate, high-performance production tooling at a fraction of the cost and often in half the time, compared with traditional techniques. Furthermore, the process can be completed with minimal involvement from a toolmaker, without any sacrifice to the integrity of the finished tool. It removes some of the worry regarding the reduced skill base in this area, while also enabling us to better deploy the existing toolmakers we do have, and increase production throughput on other less complex tools."