Background

A manufacturer—specializing in precision milling and turning of conventional and exotic materials, serving the aerospace and defense industries—contacted their Okuma distributor and shared that they had a challenging group of parts, and needed to find a way to lower total cost. The distributor visited their facility and realized that these were indeed challenging parts and that more was needed to provide a better total manufacturing solution than just an Okuma multi-function machine. This customer was already using a competitor's multi-function machine to make the parts, but a different and more complete solution was needed. Partners in THINC was put into action.

The customer's objectives were identified as follows:

1. Provide the opportunity for 3+ machines to be maintained by one operator and for hours of un-manned operation while producing zero scrap.
2. Reduce the currently defective part percentage from 20+ percent to less than 1 percent.
3. Reduce change-over time to as close to zero as possible.

After reviewing the parts and several meetings/conversations with the customer and distributor, one of Okuma's Application Engineers started formulating a plan to make the group of parts. Several members of Partners in THINC – Kennametal, IEMCA, Caron Engineering, ChipBLASTER, Renishaw, Hainbuch, Zoller, and DataZen – were engaged very quickly to assist in formulating a better approach to making the parts.

Manufacturing

The parts are made from stainless steel and have several challenging features including 4 holes approximately 3mm in diameter drilled at an angle thru one end to intersect to a through bore of approximately 7 mm. Given that the part was around 52mm in diameter on one end and less than 12mm in diameter on the other end, created some interesting workholding and tooling challenges.

An Okuma Multus B300-W was the multitasking machine chosen to make the parts because of its tremendous flexibility and rigidity. It allows for all turning and milling to be performed in the same operation since both the right and left spindle can be used to complete the parts. The Multus has a tool-changer similar to a machining center, thus allowing for several redundant tools, which are preset on the Zoller tool pre-setter to be available while allowing changing of worn tools without any interruptions to the machining process.

Adding an IEMCA bar feeder allowed hours of un-manned operation time since more material could be loaded into the work cell. The use of stainless bar-stock provided a lower raw material cost per piece as another benefit.

The use of a Hainbuch quick change collet system solved the need for secure workholding and made change-over from one part to another possible in seconds, versus minutes. Kennametal provided the tooling for these parts on the customer's current process and proved to be an excellent choice on the Okuma as well. A ChipBLASTER high-pressure coolant system was used to extend tool-life, provide the surface finish, and chip evacuation needed to prevent the need for further finishing operations.

Caron Engineering TMAC (Tool Monitoring Adaptive Control) allowed for real-time monitoring of cutting speeds and tool life. DataZen's MacMan-Net provided real-time production related data collection that was transmitted directly to computers or PDAs for supervision and production scheduling. Renishaw probing was used to ensure that all critical dimensions were being held on each part prior to proceeding forward, while post process gauging was provided by the customer.

Results

1. The use of the IEMCS bar feeder, Renishaw probing, Okuma's Multus with multi- redundant tooling capability on the critical tools, and advanced solutions like Caron's TMAC made up to 4 hours of unattended operation possible.
2. Part size variation from last part produced one evening to first part produced the next morning after complete machine shut-down and no warm-up period the next morning was confirmed by the customer as 0.0001”. The customer previously had an employee come in early each day to start the machines in a warm-up cycle prior to starting production. The Okuma Multus with its advanced TAS (Thermal Active Stabiziler) systems eliminates the need for such warm-up cycles. This not only reduces labor cost, but it also reduces energy usage by approximately 5%, thus allowing for some GREEN savings for the accountant and the environment.
3. When part change-over was needed, the Hainbuch collet system was easily changed in seconds. The savings from using bar-stock versus slugs made it possible to virtually eliminate time lost to loading/unloading through application of the IEMCA bar feeder, and Okuma's integrated parts catcher to remove the finished part from the machine without the door every being opened.
4. Using the Zoller pre-setter and feedback from the Renishaw probe virtually eliminated operator input for tooling off-sets. This reduced the possibility of off-sets being made in the wrong direction, or to the wrong tool.

Additional benefits were extended tool-life through the use of high pressure coolant and real-time tool load monitoring, provided by ChipBLASTER and Caron Engineering respectively. Pre-set tooling assemblies from the Zoller pre-setter eliminated the need to “touch-off” and adjust after making tooling changes. Real-time production data sent to desktop computers and PDAs allowed management to constantly be aware of how their investments were performing.

This customized manufacturing solution was capable of 80% more output in the same 8 hours shift, while allowing more machines to be operated by a single operator. With the operator intervention virtually removed from the process, the part defect rate was reduced to less than 1%.

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