Aluminum Alloy Output Arms

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Output Arms
Output Arms

The name American Precision Gear Co., Inc. is well known throughout many high tech industries for more than gears; our advanced machining capabilities allow us to provide a wide range of precision components. Though this part did include a broached spline, it also highlights our general machining, finishing, and assembly capabilities. The part is a micro servo output arm for an aerospace application; this one was being used in a high-altitude UAV. This type of high-value part requires high precision with absolutely zero defects.

In their search for a company that could complete in-house all aspects of this project, the customer qualified only three manufacturers. We were awarded the contract because of our extensive record of quality and commitment to investing in new processes that allow us to deliver superior value. In this case, we invested heavily in training and re-tooling; this effort ensured that we could provide exactly what the client required year after year.

This piece began with 2024-T351 aluminum alloy, which was milled on our Doosan CNC 5 Axis DNM 400 Mill. To form the spline, we used an O'Brien 12 ton broaching machine, and as an alternative we also used our Lorenze 152 CNC shaper. This step required the development of very specialized tooling to ensure precise spline alignment. The finished piece featured a 16 tooth spline with a 48/49 pitch and a 30° pressure angle. The overall part length was 2.8245" to 3.2975", .900" in width, .585" in height, all machined to tolerances of +.005"/-.001". However, the finishing requirements are what really set this project apart.

Once the parts were found to be 100% defect free, we moved on to finishing; the customer’s specifications called out a MIL-C-5541, Class IA, yellow chemical film coating, followed by a MIL-A-8625, Type II, Class 2 black anodizing. The application of these two coatings required us to fabricate and apply intricate masking that would ensure no bleed off of either finish. The assembly portion called for the insertion of a bearing and part marking.

Throughout this project, our quality system played a crucial role. During machining, dimensional verification was provided through our Micro Vu Excel visual comparator and gage inspection, and the finished parts were inspected on our CMM. These QC steps provided the basis for certificates of conformance that we provided the customer. Currently, we produce this item at a rate of 2500 pieces annually, at 400 pieces every eight weeks.

For more information on this project, or the processes used to manufacture it, see the table below or contact us directly.

Output Arm Details

Project/Product Name
Aluminum Alloy Output Arms
Project/Product Description
From start to finished assembly w/ bearing and helicoil
Servo mechanism arm for high altitude UAV
Capabilities Applied/Processes
CNC Milling
Spline Broaching
Spline Cutting (Alternate)
Chemical Filming
Black Anodizing
Part marking
CMM Inspections
Equipment Used to Manufacture Part
Doosan CNC 5 Axis Mill DNM 400
Lorenze 152 CNC Shaper (alternate to broach)
O'Brien 12Ton Broaching Machine
Crest Untrasonics OCJ parts cleaner
Micro Vu Excel visual comparator
Overall Part Dimensions
16 Teeth, 48/96 Pitch, 30° Pressure Angle
Length: 2.8245" to 3.2975"
Width: 0.900"
Height: 0.585"
Tightest Tolerances
+ 0.005" / - 0.001"
Material Used
2024-T351 Aluminum Alloy
Material Finish
Chemical Film per MIL-C-5541, Class IA, Yellow
Black Anodized per MIL-A-8625, Type II, Class 2
In process testing/inspection performed
Dimensional Inspection, Gage Inspection
Certificate of Conformance Reports
Industry for Use
Aerospace High Altitude UAV
Approx. 2,500 annual
Delivery/Turnaround Time
400pcs per 8 Weeks
Delivery Location
Standards Met
Customer Specifications, 2D CAD Drawing

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