Revolutionary toolmaking facility incorporates scanning technology

Malaysia-based Mattel Tools (MTSB) is the largest in-house toolroom facility of Mattel Inc, the internationally renowned toy manufacturer, famous for its ‘Barbie’ and ‘Hot Wheels’ products. It is also one of the largest tool shops in Asia. Established in 1985, MTSB produces more than 1,100 high quality moulds annually - all Class 1 or Class 2 tooling of more than 1 million shot life expectancy. Ranging from 60 to 500 tons, they include complex slide, multi-cavity and hot runner moulds. Josephine Ong* investigates.

To maintain its market leading position, MTSB has recently introduced a revolutionary production line method for building tools. High volume, multi-cavity moulds are now produced in 18 days instead of the traditional 10-12 weeks, and 3 finished tools are output every working day. Fenton Allen, managing director, talks about his revolutionary production line that has opened a new chapter in mould making.

In most tool shops, significant time is lost while waiting for machine availability. Careful planning of job activities fouls up when a job takes too long at a specific machining location. To accommodate these bottlenecks, shops buy more machines instead.

The production line concept, although not new in itself, is not easily modelled in the mould making industry. The problem has always been how to produce tools on a production line when each mould is so unique.

"To solve this problem, it requires us to completely re-engineer the way we plan and build moulds. It also requires fast and accurate machines that can support this new way of building tools," says Allen.

The production line

The first step to introducing a production line is to take a closer look at the general process flow for building a mould. This includes designing, pre-machining, CNC machining, drilling ejection, heat treatment, EDM (electric discharge machining) and assembly.

The team, guided by P. K. Vijayan, project manager, establishes 18 standardised work activities known as 'workstations', which every tool will have to go through the moment the design is approved. The design engineers will have to design the tooling to 'fit' the process. For example, all activities that require a machining centre, must be completed in that station and in one shift, prior to moving over to the next station. This facilitates a smooth flow with no bottlenecks and backtracking and is essential for the production line concept to work. Machine scheduling becomes unnecessary and a proper balance of capital intensive equipment can be maintained.

To successfully go through a line operation, the reference datums for the job must be established and maintained throughout the build process. In fact, conventional tooling methods incur a significant amount of time finding this reference datum at each set-up.

"Here we have our reference datum set and locked in, at each of the 18 stations. Each machine has a 'Master Datum' and all movements are referenced from that permanent master location," explains Vijayan.

When a project is initiated, an 'Electronic Master' location is established in the part geometry. In the case of electronic models, the computer locks in this part datum. MTSB chooses Cimatron as its NC programming system both for its ease of use, and ability to mesh well with the company’s ProENGINEER CAD system and the production line.

Many of Mattel's toys, however, rely on sculptures, which necessitate the use of resins to produce the required tool. A Renishaw Cyclone scanning machine is used on each production line to input this required geometry. As well as rapidly creating point cloud data, the Cyclone system also establishes part datums, which eliminates the need to surface the point cloud information. Renishaw’s TRACECUT Software, supplied with Cyclone, controls the scanning process and is used by MTSB to generate cutter paths for the machine tools, directly from the point cloud data. The system automatically provides a datum for the part geometry that can be merged with the master datum for each of the 18 workstations.

At Station 1, also called 'Process Control', the engineer designs the tool and plans the build sequence. Templates of each workstation are on the file in the 'Process Control' computer. The part is laid onto each template master datum and all operations make reference to this common point. Once the required operation is determined, it is then batched and sent to the appropriate workstation.

The remaining steps are designed to move the steel quickly, from workstation to workstation. Each block of steel is mounted to an Erowa mounting plate and every station has an Erowa holding device. The mounted steel is dropped onto the holder and 10 seconds later, the machining starts! Because all of the master data is pre-determined, no time is required to confirm the location. This means the machines are constantly running.

"Constant up time is something we all look for in capital intensive machinery. Of course, this also puts a high demand on our machines," says Vijayan.

MTSB uses the Makino MAX 65 for machining operations and the Makino EDNC 43 and EDNC 65 for its EDM operations. These machines prove highly reliable under the demands of constant running. They also operate accurately and consistently, meeting all repeatability requirements that a sequential line operation demands.

Tool components travel from one operation to the next via a roller conveyor. At the end, components are assembled and transferred to the injection moulding machines for testing.

Quality assurance confirms part and tool compliance - all in 18 days. The parts are forwarded to the engineering team for evaluation and functional tests. Upon final approval the tools are shipped to the various manufacturing sites where they are typically expected to exceed two million shots.

"Presently, we have three production lines and we operate only one shift. We are studying the advantages of running the lines on a three-rotating-shift basis to further reduce tool-build time. With 58 people, the production lines are presently able to produce more than 750 tools per year. By year end, the entire factory will be converted to line-type operations. We hope to achieve double digit growth," says Allen.

Advantages

The standardisation of work activities first requires a design engineer to fully utilize his software capabilities. This expands his knowledge and value-adds his contribution to product design.

It also allows the company to fixture and automate set-up sequences. Since set-up constitutes more than 50% of the tool-build time, dramatic reductions in lead time and cost are realized.

The well organised work flow raises efficiency and productivity and eliminates bottlenecks as well as conventional job scheduling required to maximise machine capacity. Intake of short-notice orders is now made possible. MTSB once produced a 200-ton, 8-cavity mould in 36 hours. Machinists, rather than toolmakers, are employed to operate on the CNC machines. This helps to keep labour costs down as toolmakers are difficult to find and expensive to employ.

Very successful

It has been more than a year now since MTSB started the concept of building tools on a production line.

"The success of production line tooling is getting the product rapidly to the market. It is not just having faster and better equipment, but successfully applying new machine technologies to maximise their performance capabilities," says Vijayan.

"We have successfully reduced the lead time, from 7 weeks to 18 days, for tools of less than 125 tons. We are now ready to announce the reduction from 10 weeks to 18 days for those of 250 tons and below."

The new production line for these mid-size tools (125 tons and below) looks just like the other two lines that are already producing two moulds every day. "It's more than just putting a line at the shop floor. We have in place an infrastructure; the way each machine networks with one another; the software that blends all the machining activities plus a unified workforce that is ready to brave any new challenges. The result - a synergy that is not easily emulated," says Allen.

Whether ultimately the production line concept gets copied into other mould shops, MTSB's staff is not too concerned. What they are concerned about at the moment is how to further reduce lead time and tool cost without sacrificing performance quality.

*Josephine Ong is a staff writer with Singapore based journal, Asia Pacific Metalworking Equipment News.