This technical information has been contributed by
Precision Enterprises

Illinois Company Supports OEMs with Finished Aluminum-Alloy Sand Castings

Sand Casting

Specialties Include Proprietary Alloys, In-House Engineering, and Automated Casting and Machining

A 65-year-old, family-owned company near Chicago has found a unique niche in the field of sand casting, evolving into a one-stop shop for customers that need precision, finished parts. Precision Enterprises, situated in Warrenville, Illinois, is able to manufacture custom-made parts, handling everything from initial design to assembled parts that are ready to deliver.

"We're very good at running short and medium production runs and also at running parts that are very difficult to produce," says Jim Schrader, owner and president of Precision Enterprises. "We can produce custom-made castings out of a number of different aluminum alloys, and in just about any size and quantity a customer would want. And with our machining centers and lathes, we can handle all of the machining, as well as secondary and finishing processes."

Precision Enterprises was founded in 1945 as a pattern and tooling shop on the west side of Chicago by Jim's father, Cliff Schrader, and his grandfather, William Schrader. A few years later, they poured their first sand casting in the backyard of the pattern shop. Today, Jim and his brother Bill run the business, which has grown to 85 employees situated in four modern production plants and an office building.

The company initiated the process to become a one-stop shop about five years ago, when it brought in two highly-skilled design engineers to add to its complement of tooling engineers. Capital investments in new automated casting and machining equipment, including two very high-speed, large horizontal machining centers, were also set in motion. And within the last couple of years, Precision Enterprises has started its own polishing department because its dental and medical equipment parts needed a very high luster. However, most secondary and finishing processes--including heat treating, anodizing, wet painting, and powder coat painting--are handled by outside vendors. The company has also set up a subassembly area, where it handles about 80% of mechanical assembly.

"We specialize in very cosmetic, high-quality, aluminum alloy sand castings with extensive machining," Jim Schrader explains. "What I mean by cosmetic are castings that will usually be painted, anodized, or polished."

"We're able to do primary operations in-house that other casting companies would have to send outside," says Mike Schrader, sales manager at Precision Enterprises. "And our ability to give our customers engineering assistance in the design stages helps us cut costs and turnarounds for them."

Its ability to function as a one-stop shop has served the company well in its work for OEMs. In one instance, an oven manufacturing company needed parts for a large door and a heating-element housing. The OEM was having the castings made in Pennsylvania, then shipped to Canada for machining, and then shipped to Ohio to be painted. "They had long lead times that they couldn't control, and a lot of tracking to see what stage of production the parts were in," Mike Schrader remembers. "And they also had a 5% scrap ratio at each supplier from parts not properly manufactured.

"So they came to us for a solution, and we said that we could handle all of the processes for them. We discussed ways that they could reduce the cost of the parts by reducing their weight and cutting the cost of tooling, and when we were finished with the parts, the scrap rate was reduced significantly. After the first production cycle, we were able to cut 15% from the overall cost of the parts. Not only were we able to cut down on machining times, but we also cut down on all of the logistics and excess time by doing the parts entirely at our facility. And we were able to cut about three to four weeks off of the project for them."

Precision Enterprises' primary markets are medical equipment, outdoor lighting fixtures, construction equipment, automotive parts, and analytical equipment. The company makes parts used in surgical operating tables, dental equipment, and overhead lighting fixtures for operating rooms in the medical field. For analytical equipment, applications include laser types of devices that are used for analyzing or testing almost anything from blood samples to hard metals. The company also produces many different types of control valves and housings, as well as gear cases for earthmoving equipment.

"One area that we specialize in that not too many companies are involved in is using very large molding machines that allow us to do parts that range to about 30 x 60 inches," says Jim Schrader. "And we also specialize in doing work with a number of different types of alloys. To do this, we have multiple furnaces so we can dedicate each one to a different alloy. We also have automated molding machines that automatically feed the sand into the mold cavity and then take it out. Then it turns the mold over and discharges a mold ready for pouring. As the mold moves down the production line, it is poured automatically when it reaches the furnace. So everything is handled with very little human intervention."

The ISO 9001-certified casting and machining company is able to remain cutting edge these days with an in-house engineering capability and state-of-the-art design and engineering software.

"We are able to work with just about any modeling software that a company would be using," Jim Schrader maintains. "We have software we can use to analyze their computer models to check for areas like draft, metal flow, and wall thickness. Then we'll make recommendations for changes that will make the part more manufacturable and economical. Once approved by their engineers, we'll go into production of the mold tooling from their 3D computer model. At the same time, we can use the data to build fixtures to hold the parts. In the past three years, we've switched over to producing our tooling from 3D computer models, and we've created some of this software on our own. With this software, we can create the tooling, fixturing, and machining paths from their 3D models."

A Faster Route to Prototypes and Short Runs

Sand-cast parts are not made to the same degree of precision as die castings, but the tooling cost for sand casting is about 40% to 50% less than for die casting, a process that uses hard steel tooling. And because the aluminum tooling for sand casting is precision-made, it allows a mold to be made out of sand and bonding materials. Sand casting is also a quicker way to get parts up and running for prototypes, and is a good process for outputting small and medium production runs of several thousand parts per year.

"The repeatability of close tolerances is also much better for sand-cast parts nowadays because of the automated foundry equipment being used," says Jim Schrader. "We've cut tolerances in half compared to what they were about five years ago when casting was done manually." He says that the company can hold tolerances of +/- 0.003 inch on tooling, and +/- 0.005 inch to 0.010 inch on the mold. Tolerances for repeatability are about +/- 0.0015 inch.

Machinability a Key Issue in Part Design

The machining of sand castings brings added precision to parts that will have critical uses. Because Precision Enterprises machines most of the castings that it produces, its machining department gets involved at the beginning of the design process. Machining personnel will review the design to make sure that the casting can easily be machined. They'll check to make sure that gating is not installed on a critical surface. Gate placement is also very important when building part holding fixtures.

"We've made our machining centers very easy to set up by using hydraulic fixtures that can be set up very quickly," Jim Schrader explains. "We want to be able to run several jobs per day on one machine, so this type of automated fixturing helps us to do this. One of our machining centers gives us the ability to do five-axis machining, which is very efficient and quick when there are many different, complex radiuses on the part."

Palletized loading and unloading of parts with high production runs create additional machining efficiencies. If the company has a long-term relationship with a customer that calls for large orders on a regular basis, it will set up palletizing for those projects. Company managers say that they've cut machining set-up times by 50% with palletizing.

Alloys Customized to Specific Property Requirements

Another area of concentration is the company's use of specialized, proprietary aluminum alloys. Although aluminum alloys 356 and 319 are standards, Precision Enterprises also often uses alloys that have magnesium content, such as aluminum-magnesium alloy 535. The magnesium is said to give the alloy much greater strength and higher elongation, allowing the part to bend rather than break. Documentation is always obtained from the lab to certify the metal's chemistry. The company is currently making a couple of military parts that have to pass stringent ballistics tests, so they require a very high material strength. To achieve this, the company's engineers changed the chemical composition of the aluminum alloy to make it stronger.

"The 535 is used in a lot of outdoor applications where corrosion resistance is also important," says Jim Schrader. "Our engineers work with an outside metallurgical lab on a daily basis to control these specialized alloys, which most of our competitors are not using. We will start with a standard alloy used in the industry, and then change the metallurgical content slightly to create other properties in the material."

Another success story for Precision Enterprises is its production of a turbocharger, used on Mercedes Benz automobiles, for Honeywell International. The OEM originally came to Precision Enterprises with a part that was designed for die casting and permanent molding. Honeywell was given a turnaround time to get hard steel tooling and final parts made, but didn't believe that it would have enough time to get the parts finished by the deadline. Also, because the design was already approved, the company couldn't change any aspects of the design. In order to secure the contract, Precision Enterprises would have to handle certified leak testing for the parts.

The wall thicknesses seemed to be too thin to use a sand casting, but the casting company's engineers persevered to find a way to make it happen. "We found out we could do the precision parts for them with our sand casting process, and we set up the leak testing operation in-house with the help of Honeywell's engineers," Mike Schrader recalled. "We were able to produce aluminum tooling very quickly for them, and we stuck with the original design for thin walls, complex geometry, and holding high pressures inside the part. We were able to get the finished, tested parts to them within a six-week time frame. Before this, they were told they would have to wait six weeks just to get the tooling finished. We saved them about 30% on the overall cost of the parts by using our aluminum tooling, and reduced the overall turnaround times on the part by about four weeks."

For more information, contact Jeff Smith at

This technical information has been contributed by
Precision Enterprises

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