Case Study: CNC Mill-turn Machining for High Precision Low-Volume Disc Parts
Learn how WayKen manufactures high-precision, low-volume custom disc parts for various devices and equipment and ensures quality results from FAI to final production.
At a Glance of the Project
| Information | |
|---|---|
| Product | Precision Disc Parts |
| Challenges | Tough tolerance of total runout, parallelism and flatness, high internal threading accuracy |
| Technology | CNC mill-turn machining |
| Material | AL6061-T6 |
| Quantity | 640 pcs |
| Lead Time | 30 Business days |
About Disc Round Part Types
Disc parts are common parts in a variety of machines and equipment, such as a variety of end caps, catch plates, flanges, and flywheels. Today we are going to introduce how to machine low-volume customized disc parts with high precision requirements.
Unlike prototype parts, before carrying out low-volume production, manufacturers should propose and formulate a set of specialized machining programs. And the program needs to be tested and verified repeatedly until every detail is confirmed.
There are many factors that should be considered when formulating a program, such as how to optimize the machining process to improve production efficiency, how to ensure machining accuracy and control quality during the production process, and so on.
How to Prepare for Low-Volume Production?
When WayKen received the customer’s order, we started to formulate the processing program promptly. A series of standards have been developed for the acceptance of raw materials, optimized processing routes, controlled quality, etc. In the production process, we also summarized the machining key points and proposed suitable solutions.
In this case study, let’s take a close look at the machining key points of a case of low-volume disc parts and WayKen’s solutions, and hope to give you some inspiration for your projects.
Analyze Parts and Determine Machining Process
The machining of high-precision disc parts is a laborious process, and disc parts that are in the prototype verification stage will be machined by turning usually. But from the drawings you can see that this part has 6 threads and 6 holes that need to be manufactured, which can’t be machined with a lathe only. They need to be second-clamped to a milling machine, which is very inefficient for manufacturing 640 parts.
After confirming all the requirements with our customer, WayKen chose to machine this low-volume project by mill-turn machining.
Ensure Assembly Surfaces
According to the structure of the disc part, the back sides of the part have 6 holes each. The A and B sides have a tough tolerance of parallelism, and the reverse A side has a tough tolerance of flatness. At the same time, the outer cylindrical surface and B cylindrical have a tough tolerance of total runout. So, after evaluation by our engineers, these two surfaces are considered important assembly surfaces.
Flatness Tolerance of A Surface
As you can see in the drawing, the A surface requires a flatness tolerance of 0.001 to ensure assembly and to serve as the inspection datum. In order to achieve this flatness requirement, it needs to be machined by fine-turning serval times, progressively removing excess material. Then, inspect the A surface several times until the flatness 0.001 can be ensured.
Total Runout and Parallelism Requirements
The outer and B cylindrical surfaces of the part need to be assembled with the bearings. In order to ensure a precise assembly and smooth running of the bearings, high requirements for total runout and parallelism with the A surfaces need to be met.
As the drawing is marked, the total runout tolerance is 0.0005 between the outer cylindrical surface and B cylindrical surface, and a parallelism tolerance of 0.001. To achieve these requirements, it is very important to find the datum for positioning.
As mentioned above, we have machined the high flatness requirement of surface A by several fine-turning processes. Surface A will be used as the datum for testing this total runout and flatness tolerance, turning the outer cylindrical surface and the B cylindrical surface and the small step between them, so that we can achieve the requirements.
Machining Threaded Holes
This disc part needs to fit perfectly with other parts, so the concentricity tolerance of the threaded holes is tough. To achieve this concentricity tolerance, we also should locate the datum for positioning and machine the threaded holes with precision milling.
How to Take Precise Points to Get Accurate Inspection Data?
The tough total runout, flatness, and parallelism tolerance we mentioned before are not only key points of the machining process but also major challenges for inspection.
Parallelism Inspection of Small Step Surface and A Surface
As the following pictures show, it is difficult to take points on the small step surface. WayKen chose to use a fixed device to accurately fix the parts on the inspection table (as shown by the clamping). Then using multiple styli heads for measuring the parallelism of the two surfaces.
Total Runout Inspection of Outer Cylindrical Surface and B Surface
It is difficult to take points due to the undercut, the part was also fixed as shown in the right picture, big head is used for measuring the total runout.
Start Your Low-Volume Production Project with WayKen
For low-volume manufacturing projects, WayKen will send the FAI to our customer to ensure each machining required is met. After receiving the FAI part, the customer immediately tested the accuracy of the part and carried out a trial assembly, everything was perfect. So WayKen followed the machining program started the formal low-volume production, and successfully delivered.
