Batch Manufacturing for Aerospace-Grade Steel Parts with Non-Standard Geometries

About the Project and Customer

In the aerospace sector, where precision and reliability are important, even the smallest component plays a critical role. Our customer, an aerospace precision equipment manufacturer in Eastern Europe, specializes in the development of advanced systems such as satellite payloads and space exploration devices. Their products require precision parts made from high-standard materials, and they only work with suppliers that meet strict certifications.

Recently, the customer approached WayKen for the production of several core components for their R&D equipment — steel parts with complex structures and tight tolerances, produced in quantities of hundreds per part, totaling thousands. What’s more, the entire order had to be delivered within just two months. In this case study, we’ll take a closer look at one representative part and how we successfully achieved this project.

Analyzing Requirements of Structures and Tolerances

The part featured in this case may be small in size — just 68 × 68 × 40 mm — but the structure is not simple. Made from 45# steel, it required extensive material removal from a solid blank, which increased the risk of deformation. Therefore, managing this deformation became one of the key technical concerns during production.

In addition, the part featured structures on all six faces. Achieving such multi-sided precision called for carefully planned setups and highly accurate tool paths. Even more demanding were the geometric tolerance requirements between different face structures, up to 0.02mm. So, how we designed the machining sequence was critical to ensure dimensional accuracy and overall part quality.

Machining Strategy: From Datum Control to Deformation Management

With complex geometry and tight tolerances, achieving the required precision depended on two key factors: identifying the correct fundamental datum and planning a detailed machining sequence.

Finding the Fundamental Datum

When multiple tolerance relationships existed within a part, it was critical to first analyze their structure and determine the primary datum. As shown in Figure 1, the theoretical center axis of the two Ø9 holes was labeled as N, which had to maintain a parallelism of 0.02 mm with the K datum. On the opposite face (Figure 2), the axes of another two sets of Ø9 holes – X and E – also had to maintain a parallelism of 0.02 mm with K, as well as perpendicularity of 0.02 mm with the N axis. This was the most complex set of tolerance relationships for this steel part.

It could be seen that the K datum was the fundamental datum to ensure most of the tolerances of this part. We first needed to obtain the K surface with extremely high flatness, accurately machine all the structures on the K face, and then carry out subsequent processing with it as the bottom surface.

Step-by-Step Machining Sequence

Given that all holes required H7 tolerance and GD&T values were controlled within 0.02 mm, in order to meet the precision requirements, here is the stepwise approach.

1. Rough Machining with 3-Axis Machines

Before referencing the K surface, the steel part underwent rough machining on a 3-axis machine from six orientations, leaving a 0.5 mm allowance on each side. This stage focused on heavy material removal rather than precision, and since clamping was relatively simple, 3-axis machining offered a cost-effective solution.

2. Machining K Datum

Then, machined the structure of the K reference. While processing the K reference, the bottom surface of K had to be a plane with extremely high flatness. Otherwise, being processed from an uneven bottom, the K surface could not be used as a datum.

Therefore, to get a flat K surface, we first used a grinder to grind the K surface (Figure 3), rather than cutting directly. At this time, the structure of the K surface was not processed, leaving a 3 mm margin. Secondly, we turned it over and ground the K face(Figure 4). Then, we obtained a flat K surface. Finally, we used the K surface as the bottom to process the structure of the K surface (Figure 5).

3. 5-Axis Fine Machining

With the K face now established as the bottom datum, the part was mounted on a 5-axis machine for finishing. This enabled all remaining features on the other five faces to be precisely machined in a single setup, ensuring alignment and tight tolerance control.

Controlling Deformation in Hollow Structural Steel Parts

Another key focus in this project was controlling deformation — a common issue when machining hollow parts from medium carbon structural steel. This material has a high elastic modulus, meaning that internal stresses introduced during machining were likely to be released as deformation, especially after heavy material removal.

The deformation mostly occurred during the rough processing stage. Therefore, we left a 0.5 mm machining allowance on each side during roughing. This buffer not only allowed space for potential deformation but also ensured that any dimensional deviation could be corrected during finishing.

After rough machining, all parts were annealed to fully release internal stresses. Although deformation did also occur during annealing, it remained within the 0.5 mm allowance and could be precisely corrected in the finishing stage.

Finish machining involved minimal material removal using high-speed, low-feed strategies. At this stage, the part was more stable, so the deformation was tiny and did not cause out-of-tolerance issues.

From Delivery to Long-Term Partnership

After receiving the complete batch of parts, the customer acknowledged that all components were delivered on schedule and in good order, with full inspection documentation provided from WayKen. They expressed recognition for our production capacity and management system. This positive experience laid the foundation for a continued and stable cooperation that remains in place today.