Creating the perfect assembly

While the IMA process reduces costs, Craig says it also ensures assembly accuracy and strength. Part-to-part consistency, for example, is maintained over long production runs with tolerances of ±0.05 mm (±.002-inch).

In addition, the process creates a strong mechanical lock that can withstand high loads. Zamak 3 zinc alloy, the most common bonding material used, is a combination of zinc, aluminum, magnesium and copper. As such, it exhibits a hardness of up to 82 BHN (Brinell) and shear and tensile strengths of 31 and 41 kpsi, respectively. According to the company, the alloy bond can also stand up to operating temperatures of up to 230°F (110°C) and doesn’t become brittle at temperatures down to -40°F (-40°C).

The range of applications FisherTech has applied its IMA process has been extensive, Craig says. For a manufacturing customer that makes industrial thermostats, for instance, the company solved a problem with air gaps resulting from crimping a heat sink to a bimetal strip. Using IMA, the heat sink was die cast directly onto the bimetal strip, becoming an integral part of the assembly with full surface contact.

As well as improved part-to-part production consistency, the pre-manufactured heat sink was replaced with a less expensive zinc alloy casting. Production was also increased to 400 assemblies an hour and inserts for the basic tool reduced costs for production of two different sized assemblies.

Similarly, production costs were reduced for an automotive customer by die casting a zinc alloy stepped shaft to capture a steel collar and oil impregnated sintered bronze bearing. According to Craig, adopting the FisherTech IMA process resulted in an increased production to 600 assemblies an hour while maintaining dimensional tolerances of ±0.13 mm (±.005-inch).

Craig says the company has maintained the same levels of speed, cost savings and assembly accuracy for many other applications ranging from electronics and control cable assemblies to household appliance manufacturing.

However, for companies that consistently have high-volume jobs or are required to perform assembly in-house, the company offers the option of selling a custom-designed FisherTech assembly system.

"Full training is given," he says, "and the systems are designed and built to be easily integrated into a production line."
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