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In the current competitive manufacturing environment, design engineers and procurement groups feel pressure to lower costs, enhance product reliability, and shorten production cycles… without sacrificing quality. At Austin Alloy Cast, a leading investment casting manufacturer whose primary focus is stainless steel casting, we regularly partner with customers to achieve these goals by replacing the conventional welded assembly process with one singular, Robust, cast component.

This case study illustrates how our transformation not only simplified our customer’s manufacturing, but also decreased their cost by nearly 60%, improved product performance, and increased efficiency overall.

Background: The Challenge of a Welded Assembly

Austin Alloy Cast was approached by their client, a well-known Valve manufacturer, because of ongoing issues with one of their critical components a welded stainless steel housing assembly made of multiple components that were assembled together using complicated welding processes.

While the welded design seemed reasonable at first, it started to deteriorate rapidly with significant disadvantages related to:

• Costly fabrication with multiple subcomponents, welding labour and the potential of rework. In most developed countries, there is shortage of skilled Labours.
• Difficulties in distortion and alignment as a result of weld heat input.
• Varied mechanical properties in and around the weld areas.
• Long manufacturing cycle times due to post weld machining, inspection and testing.
• Poor surface finish that required expedited machining to meet functional needs.

The customer wanted to keep the same functional design while improving strength and consistency at a lower cost and Austin Alloy Cast had the right answer with investment casting.

Solution: Replace ‘Welded Assemblies’ with a Singular Investment Cast Component.

Following a thorough feasibility study the engineering team recommended changing the welded housing assembly into a one piece, investment cast component made of a WCB/CF8M material.

The advantages of this solution included:

1. Design Simplification:

The component structure can now be created as one, nearly net shape cast product without any welded joints or assembly operations. Additionally, complex internal passageways and contours that need to be welded can now be produced directly during the investment casting process, as investment castings possess an inherent ability to reproduce complex geometries.

2. Better Mechanical Properties:

Welded parts often present heat affected zones (HAZ) with different microstructures and residual stresses, but investment cast parts are uniform and have isotropic mechanical properties throughout. The investment casting process offers better fatigue life, greater load capability, and superior resistance to corrosion and cracking.

3. Better Surface Finish and Dimensional Tolerance:

It follows that investment castings will provide a quality surface finish and tight tolerances. This provided significant machining time savings, as the part will have near net-shape finish.

4. Lost-wax process offers great repeatability:

Overall production lead time has been significantly reduced. The requirement for numerous welding, alignment, inspection, and subsequent heat treatment steps have all but disappeared, allowing for a much quicker and consistent production flow.

5. Economic Benefit:

Perhaps most impressive was the cost reduction of nearly 60% of the prior welded assembly. This was realized through material optimization, followed by the absence of multiple manufacturing steps, as well as reduced manpower and inspection time.

How Austin Alloy Cast Made It Happen:

At Austin Alloy Cast, any undertaking begins with a structured, engineering based process.

1. Design for Casting (DFC):

We worked closely with the customer’s design engineers in order to design the part geometry for casting. The fillet radii, draft angles, and wall thickness were optimized for proper metal flow and sound castings.

2. Tooling and Wax Pattern Development:

Investment casting tooling was developed to accurately match the redesigned model. Wax patterns were manufactured and assembled into trees, minimizing dimensional instability.

3. Shell Building and Pouring:

Utilizing a controlled ceramic shell process, a durable mold was created. Molten stainless steel was poured with strict metallurgical controls to achieve a uniform grain structure and density.

4. Heat Treatment and Finishing Processes:

To improve mechanical properties and corrosion resistance, the castings underwent solution annealing. Operational CNC machining was kept to a minimum to achieve final tolerances. Surface finishing, along with non destructive testing (NDT) assessed the parts for integrity.

5. Inspection and Validation Processes:

To ensure that each part would fit properly and was dimensionally correct, it was stamped upon validation using a CMM Coordinate Measuring Machine. NDT methods, including dye penetrant and radiography, helped confirm the absence of internal defects and surface defects.

Results: Tangible Gains in Every Metric

The switch from a multi piece welded assembly to a single stainless steel investment cast part resulted in meaningful and substantial improvements in all factors related to both production and performance. The most significant benefit was the significant cost savings a reduction of around 60% all due to not having to perform the several steps of fabrication: cutting, aligning, welding, grinding, and heat treatment. The part could be cast as a single component, so a highly skilled welder, a jig, fixture, and multiple inspections were not required; thus, the labor costs were much lower and the overhead directly associated with these inspections dropped to zero.

In addition, the lead time for manufacturing was less for the same reason. The investment casting process created a predictable and repeatable flow of work that eliminated the need to plan for countless fabrication processes or wait on inspection criteria. Instead, Austin Alloy Cast was able to deliver finished castings in short lead times, increasing customer turns and supply chain efficiency.

From a technical perspective, the new investment cast design exhibited better mechanical integrity and reliability. The previous welded joints were typical weak points that sometimes formed microcracking or stress concentrations with cyclic loads and thermal shifts. The investment cast component had consistent mechanical properties and performance throughout the entire component, with no weld weak points due to cracking, hardness variations, or strength.

The resulting part had better tensile and fatigue resistance and improved corrosion resistance, as well as less dimensional changes during operation. Additionally, the investment cast surface finish and dimensions from an assembly standpoint were improved over welded assembly. Also, the investment cast parts near net shape quality minimizes fabrication and tooling time, and material savings enable consistent and predictable performance/consistency.

In conclusion

This case study has shown how Austin Alloy Cast a trusted investment casting manufacturer facilitates the transition from complex welded assemblies to cost effective high strength stainless steel castings.

By leveraging our knowledge in investment casting and stainless steel castings we help industries achieve optimized designs, reduced costs, better reliability, and faster turnaround.

Whether automotive, pump, or process equipment our focus is to continue to provide precision, performance, and perfection by leveraging world class investment casting solutions. We play a role of a technical consultant for your Metal components requirements. Turns out, that is the greatest value addition we provided to our customers.