With manufacturers constantly improving the performance and reliability of their mechanical designs, they want subcontractors that can supply finished parts that reflect the accuracy demanded by the new sophistication found in these designs. In business since 1978, New World Machining Inc. manufactures products for primarily the semiconductor and medical industries. In addition to meeting machining needs, the company also provides such processes as lay patterns andother finishes. In 1944, the company moved to its 30,000ft² facility and its 50 employees work two 9-hour shifts.
New World requires precision machining capabilities by machines that are extremely rigid as well as accurate. That is why New World selected Mighty Comet VMCs for the bulk of its CNC machining center operations. New World manufactures very intricate parts that are machined, plated or hard anodized, and then machined again to very exacting tolerances- part tolerances are in the +/-0.005" to 0.0005" range.
Small runs and prototypes are key to New World's operation, but the company is equipped to handle large production runs as well. Quality control plays and important role, as a zero defect plan is used and deliveries are to JIT requirements. This entails source inspectors coming to the plant to check on quality. To ensure consistency throughout the operation, i.e. between machining and quality control, the entire facility is air conditioned.
PRECISION ENGINEERING
Precision machining starts with engineering supplying precision data. All customer drawings and CAD files are thoroughly reviewed before machining operations start. Whenever necessary, drawings are red lined and reviewed wiht the customers beforehand. In some cases design engineers are not thoroughly experienced with the unique techniques necessary to machine difficult designs. For example, to machine a pocket without a radius in the corners, it may be necessary to have holes (reverse radius) in the corners. Geovision is used for CAM programming, and a drawing is sent out with each job traveler so the machinist has a clear picture of the job being machined. Bar coding is also used to keep tabs of jobs running through the shop.
MACHINING OPERATIONS
Machining operations consist of CNC turning centers, CNC machining centers, manual mills, engine lathe and grinding machines. The largest area is the CNC machining center with Mighty Comet VMCs being the predominant machine tool. Leading the way are four VMC-1000's, followed by two VMC-1100s and one each of the VMC-1500 and VMC-520. One VMC-1000 is equipped with a 12:, full 4th axis rotary table. In addition to the Mitsubishi Meldas controller, all Mighty VMCs are equipped with high speed rigid tapping.
Because precision machining requires both skill and technical expertise, VMCs that rated high in machine geometry and construction were required. The machine had to be able to withstand the dynamic loads during cutting. Although the entire shop are is air conditioned, the VMCs selected had to be able to compensate for thermal effects. For example, the Mighty's have the ballscrews located in the exact center of each axis, thus heat and lost motion is effectively eliminated. In addition, a cartridge-type spindle is used for heat dissipation, and the spindle cooler effectively maintains the temperature of the cooling lubricant.
While controlling the thermal effects was an important factor in selecting VMCs for the company, other factors were equally important. To achieve precision machining, an accurate, stiff and stable spindle was equally important. The Comet uses a cartridge-type spindle that is made of chromium-molybdenum alloy steel that is supposed by very precise angular contact ball bearings. The spindle more than met the need for stability necessary for precision machining.
The rigid tapping feature reduces tapping time by as much as 50% over conventional tapping. A direct synchronous sensor is built into the spidle motor. The digital control achieves a perfectly synchronous rotation of the spindle and Z axis servo motor. Costly, floating-type tap holders are not required and depth control is greatly enhanced.
QUALITY CONTROL
Because of New World's pride in its precision machining capabilities and demands placed on it by the medical and electronics industries, the company emphasizes a high degree of quality in all facets of its operation. The quality program starts with the personnel. Not only are all new employees in structed on company quality techniques, but they receive ongoing training in TQM and SPC.
An important part of the operation is the use of its CMMs for checking finished machined parts. New World has two Mitutoyo coordinate measurement machines utilizing Geo Pak software. An automatic Renishaw probe allows even more precisse measurements. In addition, all machine operators are involved with in-process inspection, especially on first-article parts. Along with the production of quality machined parts, New World performs sub-assembly operations for its customers.
CNC MANUFACTURING
One of the keys to New World's operation is to keep the VMCs running production parts. The advantage of using Mighty Comets is twofold: part quality ad reproducibility. Becasue of their reliability, maintainability, and ease of programming with their Mitsubishi controllers, New World's Comets are producing parts with exceptional accuracy. Quality parts coupled with JIT delivery schedules allows New World to offer an unbeatable combination as a supplier of precision machined parts.
By: Rodney Guilbert, Operations Manager