Customized Cylinder: From Modification to Customization

Customized Cylinder Airflow Design

We all know that cylinders are widely used in automated production lines. However, in many unexpected scenarios, cylinders can also perform remarkably well through modification and customization.

In a large-scale project jointly developed by multiple companies, the Fokca team from China was responsible for developing a customized cylinder system. After detailed discussions on technical details and requirements, the Fokca team finalized the first version of the design. This cylinder is composed only of two major components—the rear end cap of an SC standard cylinder and the tube of an SU cylinder. It has no piston rod, piston, or front end cap; instead, it is directly connected to a mechanical device at the front end.

Sounds strange, doesn’t it? Without a piston rod and piston, how does the cylinder generate force? Without a front end cap, one air port is missing. And unlike single-acting cylinders, there is no spring—so how can the airflow be controlled?

This is exactly why we chose the SU “cross-shaped” tube. By drilling two small holes on the inner wall of the SU tube, we utilize the hollow sections of the cross-shaped profile to form two independent air channels. With the addition of sealing rings, the inlet and outlet air functions can be realized. Adding flow control valves at the top of the two channels allows adjustment of the inlet and exhaust pressure and speed.

In addition, because the entire equipment is designed for outdoor operation, the cylinder must withstand harsh conditions such as intense sunlight, rain, dust, corrosive media, and low-purity compressed air. Fortunately, after pressure testing, water-immersion airtightness testing, flow channel testing, and weather-resistance testing, the samples were approved and delivered to the customer for assembly and testing.

Customized Cross-Shaped End Cover

A few months later, we received feedback from the customer. They first praised the performance of the samples under normal conditions but also pointed out a problem—the actual working environment was harsher than expected. During use, the cylinder end cap frequently experienced impacts, vibration, and abrasion. One of the sample cylinders showed a crack at the bottom of the rear end cap.

Upon receiving the customer’s feedback, the Fokca team immediately held a special review meeting. After a comprehensive evaluation, the team concluded that no standard cylinder end cap available on the market could maintain stable performance under such extreme conditions for long periods. Therefore, we decided to design a custom end cap for this product.

End Cap Manufacturing

The new end cap retains all the functions of the SC standard end cap but includes targeted enhancements. The original hollow structure was redesigned into a solid, thickened structure. The air port size and thread length were modified, and a steel hex socket plug was used.

Initial estimates showed that the end cap weight nearly doubled. To reduce weight and improve the overall aesthetics of the cylinder, we designed the end cap with a cross-shaped pattern, removing unnecessary material and reducing the weight by nearly 40%. A small flat surface was machined on one side to drill threaded holes for better installation of the plug.

Surface Treatment

Finally, the entire end cap underwent sandblasting followed by black hard anodizing.

Why this treatment?

Sandblasting: Removes machining marks and increases the surface area by about 30%, enhancing the adhesion of the anodized coating and creating a synergistic effect.

Black coloring: Combined with sandblasting, it gives a refined matte black industrial texture. The black layer absorbs UV rays to protect the substrate, and its non-reflective surface reduces heat absorption during outdoor use.

Hard anodizing: Forms a thick, durable oxide layer to enhance wear resistance, surface hardness, and corrosion resistance. It can withstand friction, rainwater, and mild acidic or alkaline environments, greatly extending service life outdoors.

Value Chain of Customized Products

Six months later, the customer's equipment department reported that the second batch of cylinders was easier to install than the first batch and that all units operated with no leakage, no corrosion, and no deformation, despite zero maintenance. Additional batches are currently in production.

The second-generation product cost only 6% more, yet achieved comprehensive improvements, especially in durability, with an estimated 2.5× increase in service life—reducing the overall lifecycle cost by approximately 65%.

We deeply realized that transitioning from “modifying an existing design” to “redesigning for functionality” is a fundamental leap. Today, each customized unit works quietly within its outdoor equipment—our greatest form of recognition.