This technical information has been contributed by
New Jersey Precision Technologies Inc.

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Machining Firm Delivers Plastics Extrusion Tooling Quickly

Plastics Extrusion Tooling

A Mountainside, N.J., firm completes plate dies for polystyrene point-of-purchase displays in 24 hours, filling a point-of-purchase industry need to speed products to market.

The customer e-mails a CAD file. Engineers at New Jersey Precision Technologies Inc. (NJPT), Mountainside, N.J., start designing the tooling the day of receipt. A proprietary artificial intelligence-based expert system translates the CAD file into the CNC control of one of 12 Mitsubishi wire EDM machines. Working unattended through the night, a System 3R pallet loader robot loads blanks into the EDM machines to shape dies to be ready for shipment the next day.

Bob Tarantino, NJPT founder and president, says this job might take three days at other extrusion tooling shops that lack robot loaders and this number of EDM machines. Other shops' one or two machines might be too busy to take on the extra work. Of the handful of machine shops dedicated to designing and building extrusion tooling, Tarantino says most own either EDM or CNC milling machines, but rarely both. NJPT is also tooled with six vertical and horizontal CNC machining centers, and the skills to combine the two processes to achieve streamlined extrusion tooling.

Broad Technical Capability

The above example illustrates this high-tech machine shop's quick turnaround and technical capabilities relating to a wide range of equipment and software. New Jersey Precision Technologies focuses on making extrusion tools for point-of-purchase products (price channels, displays, slat walls), window lineals (tracks and frames), medical applications (catheters), and various commercial products. The 25-person shop already has a large stake in the medical industry, mass producing items such as bone screws, end effects of catheters, tools to fabricate angioplasty catheter stents, and other custom parts. One of its specialties is to produce the consistent high-tolerance diameters of catheter tubes.

In addition to EDM, a Brown & Sharpe digitizing coordinate measuring machine (CMM) "reverse engineers" a tool or sample plastic extrusion without a blueprint or CAD file. The customer sends his part; the digitized 3-D geometry from the CMM goes directly into NJPT's AI-based software and CAD/CAM system to calculate tool paths to machine an exact duplicate.

The artificial intelligence-based expert system, developed by Tarantino, controls his EDM machines and machining centers, translating CAD or 3-D solid modeling data into CNC cutting programs for production. The system automatically interprets the geometry and textual notations in a customer's CAD file, eliminating the need for engineers or operators to program machine tools and continually re-check data. The program automatically checks errors, and analyzes and identifies any conflicts in data that would affect machining of the part.

Tooling Increases Extrusion Feed Rates

Tarantino says his tooling designs and manufacturing techniques increase extrusion feed rates for many materials, such as rigid PVC, polycarbonate, polystyrene, and acrylic. Tooling designs are matched to the material, the operating feed rate, and particular extrusion machine. "When a customer gives us his design for a die, transition and vacuum calibrator for extruding rigid PVC, we know which features to polish or streamline; we know the material, the melt point, and where it's going to burn," Tarantino says.

New Jersey Precision Technologies designs dies, transition plates, sizers, and vacuum calibrators that are smooth and streamlined in transitioning from round to other 3-D shape, yielding laminar flows of plastic that raise extrusion rates as much as 25%. Tarantino accomplishes this with a commercial 3-D solid modeling package from which the AI-based software translates instructions to NJPT's CNC milling and wire EDM machines. Other extrusion tooling companies, Tarantino says, sculpt such transitions by hand with files and chisels, falling short in smoothness and preciseness.

NJPT turns to 3-D solid modeling again in designing co-extrusion tooling. The solid modeling package allows the engineer to track the introduction of the second plastic, verify the plastic flow, and eliminate dead zones and hot spots. Complex co-extrusion tooling is built in three days, whereas other shops might take three weeks using die grinders or manually controlled Bridgeport machines, Tarantino says.

The company improves some extruders' cooling rates by building aluminum vacuum calibrators lined with stainless steel. The coolers gain the wear resistance of stainless steel plus the heat sink properties of aluminum, while saving costs for extruders. Conventionally, Tarantino says, vacuum calibrators are made solely from aluminum, brass, or stainless steel.

Cooling and extrusion rates rise again as NJPT's wire EDM machines cut extra water cooling channels through aluminum vacuum calibrator blocks. By contrast, other shops having only one or two wire EDM machines are unable to free machines for this extra work.

New Jersey Precision Technologies slots vacuum calibrators by wire EDM, as opposed to the common practice of cutting them with a band saw. Wire EDM attains repeatable control of slot width to 0.001 inch, which a band saw can't match. The precise amount of vacuum cools the plastic for extrusion feed rates to increase.

Electrical discharge machining, avoiding physical contact between the wire and part, generates no burrs that can scratch the plastic. An electrode removes metal using energy generated by sparks between the electrode and work piece. Wire EDM cuts metal with a thin wire electrode that follows a programmed path, creating a contour in one continuous operation. As the wire feeds from reel to reel, sparks of electrical energy progressively erode the work piece along a path determined by the relative motion of the machine's axis.

Stocks Standard Steel Blanks

As another way of delivering a tool within three days, NJPT stocks stainless or cold-rolled steel blanks in standard round or rectangular shapes for making dies, transitions, feed heads, cutter bushings, downstream coolers, and calibrators. Tarantino boasts that he can pull from his shelf a blank of the required material, of the required thickness, and turned to size. "Most shops have to start from scratch on these items," he says. "I only have to machine the center portion."

The company tries to supply to extruders feed heads with pre-drilled mounting holes. With its Brown & Sharpe CMM, NJPT digitizes customers' feed heads or die holders and mounting-hole patterns. Entering the CMM data into the CNC control, NJPT drills the holes with one of its vertical machining centers.

The extruder saves time and effort by avoiding measuring and drilling the mounting holes himself. "He only has to bolt the feed head onto the extrusion machine and he's running within minutes," Tarantino says. "The job goes better, cleaner, and quicker." NJPT also retains electronic DXF and GES files of all work performed, which can be called up years later if the customer needs to make modifications.

Tarantino claims that NJPT's services can reduce extruders' tooling requirements. Many extruders, constantly needing tooling, can't fill all their needs in-house. In particular, they lack EDM. "We can complete more parts economically, faster, at higher quality," says Tarantino. In a number of cases, NJPT functions as the extruder's tool shop. Some extruders have eliminated their tooling departments by jobbing out the work to NJPT. Others have reduced their complement of machinists and reassigned machinists to other jobs. New Jersey Precision Technologies' rapid process helps puts extruders on the fast track.

This technical information has been contributed by
New Jersey Precision Technologies Inc.
Click on Company Name for a Detailed Profile

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