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Casting Process Produces Parts with Thin Walls

A western New York aluminum casting company is using a technique more advanced than traditional sand casting to produce parts with smoother surface finishes, tighter tolerances, and thinner, vertical walls. The company is TPi Arcade, Inc., and its technique is called V-Process casting.Get more news about Sand Casting Parts,you can vist our website!

TPi Arcade (www.tpicast.com) operates a 55,000-square-foot foundry that makes parts for the medical, robotics, marine, semiconductor, power electronics, and electric vehicle markets. The company also manufactures parts used in aerospace, defense, heavy equipment, transportation, and instrumentation applications. Its castings range from a few ounces to 150 pounds.

“It’s technically a sand casting, but more innovative,” said Erik Depczynski, a mechanical engineer and technical sales manager at TPi Arcade, describing the firm’s V-Process casting technique in a telephone interview. “It’s a refinement, an improvement. V-Process offers unique advantages, such as highly cosmetic finishes, thin walls, tooling flexibility, the ability to cast vertical walls, and most importantly, speed to market.”

The company employs about 65 people, including five full-time, degreed engineers who assist customers with design for manufacturability. It offers rapid prototyping, CAD/CAM design assistance, a first article often within two to three weeks, and the first production run two weeks after approval, Depczynski said.

“Our engineers are also dedicated program managers that provide a single point of contact for our customers, from their design conception to delivery of first production run,” Depczynski said in an emailed response.

TPi Arcade provides turnkey parts manufacturing services, from casting and machining to chemical conversions, painting, powder coating, and assembly. Parts produced by the manufacturer include robotic linkages; medical cart bases; wake tower structures; heat exchangers; and housings for inverters and other electronics. The company has also manufactured instrument bases, brackets, weldment conversions, and housings for defense communication equipment.

The firm is ITAR compliant and AS9100:2016 certified for the manufacturing of aluminum V-Process castings. The scope of its certification includes melting, molding, cleaning, and heat treatment.

V-Process Basics

The “V” in V-Process stands for vacuum. V-Process sand requires no binder, resulting in a smoother and denser metal. Instead, it vacuum packs the sand between sheets of thin plastic film, according to the firm’s website. The mold’s top half—the cope—and bottom half—the drag—are draped with the plastic film, which keeps sand away from the pattern in the center being molded. That smooths the part finish. The plastic and the vacuum hold the sand in place, producing an improved finish and allowing for thinner, vertical walls.

The V-Process is similar to permanent mold or die casting, but its costs and volumes are more similar to traditional sand casting. It differs from traditional sand casting for several reasons.

The process is reported to offer surface finishes superior to those of traditional sand casting by using a fine sand without a binder. For consumer-facing products, a smooth finish is more appealing than a rough surface. The V-Process uses finer sand, which leads to a finer part finish. The surface finish is between 125 RMS and 150 RMS, whereas traditional sand-casting results in a surface finish between 250 and 500 RMS.The RMS scale represents surface roughness by measuring the root mean square between a surface’s peaks and its valleys. A lower number means the difference between valleys and peaks is smaller, so the part is smoother. A rough surface may require post-processing to smooth it out, thereby adding to cost.

A customer not familiar with V-Process might assume a minimum wall thickness is 0.25-inch. But the V-Process allows TPi Arcade to form vertical (no draft) walls as thin as 0.125-inch, an advantage that saves material, space, and post-processing costs. The narrowest walls are about 0.25-inch thick in sand casting, but they must be cast wider at the base, forming a taper or draft. “Without a taper, there is no release. It’s usually about two degrees per inch,” Depczynski said.

The draft adds extra metal, reducing the size of the interior. If a customer needs that space inside a box, traditional sand casting requires post-processing to machine the draft away. But the V-Process walls eliminate that step—thereby saving cost—because they are vertical and don’t require machining to remove draft.