Case Study | Kuroda Precision Industries Ltd.
2026/06/08
Rigorous endurance testing of ball screws is now a reality!
We are proud to offer our products to our customers!
Kuroda Precision Industries Ltd.
Kuroda Seiko leverages its expertise in gauge manufacturing, along with its in-house screw grinding machines and measuring equipment, to provide integrated production from raw materials through heat treatment to finished products.Guided by the corporate philosophy of “Challenge & Create”—“constantly taking on new challenges and creating new value”—the company supports the advancement of industry through the combined strength of its three core business segments: the Drive Systems Business, the Mold Systems Business, and the Machining & Measurement Systems Business.
〉Challenges
Durability testing for ball screws is extremely rigorous; we want to avoid situations where components such as couplings fail first
〉Objective
We need a coupling capable of withstanding severe durability evaluation tests
〉Benefits
We recommend Miki Pulley couplings to Kuroda Seiko’s customers as well! Their ability to provide technical solutions tailored to on-site conditions is also a major advantage
We need a coupling that can withstand rigorous product evaluation testing
[What Is a Ball Screw?]
A ball screw is a mechanical component that converts rotational motion into linear motion. It is particularly useful when positioning or moving heavy objects. A ball screw consists of a screw shaft, a nut
, and steel balls. The mechanism works by having the steel balls roll and circulate between the screw shaft and the nut, causing the nut to move in the axial direction.In movements where friction would normally occur, the rolling of the steel balls reduces friction, prevents unnecessary heat generation, and achieves energy savings. The range of
applications for ball screws is vast, extending from machine tools and semiconductor manufacturing equipment to industrial robots, analytical instruments, and medical devices. They have become indispensable for any equipment requiring precise positioning.
In our laboratory, we conduct rigorous evaluation tests to assess the durability of ball screws. Since ball screws are connected to
the motor’s output shaft via a coupling when installed in customers’ machinery, our evaluation tests similarly employ a mechanism that utilizes a motor and a coupling.
A fundamental prerequisite for ball screw evaluation testing is that the coupling must not fail. We were searching for a coupling capable of withstanding the evaluation testing of the ball screws developed by Kuroda Seiko—which feature high load capacity, improved maximum rotational speed, and a compact, lightweight design.
Kuroda Precision Industries Ltd.'s Side Deflector System Ball Screw AK Series
When selecting couplings, reliability in terms of durability is the deciding factor
"We also recommend Miki Pulley couplings to our customers."
When I first joined the company, my supervisor told me, “If you’re going to choose one, you can’t go wrong with Miki Pulley,” so it seems Miki Pulley has always held a special place for us. It may
have started with my supervisor’s recommendation, but in a nutshell, it comes down to our trust in their durability.
As I mentioned earlier, the prerequisite for evaluating a ball screw is that the coupling doesn’t break. In other words, we are users of Miki Pulley products ourselves before our customers actually use them.
Incidentally, the machinery shown in the photo on the right uses Miki Pulley’s “SFC (Metal Plate Spring Coupling).”
That is precisely why, when customers who have purchased our ball screws ask us, “Which manufacturer makes the best couplings?” we can confidently reply, “Miki Pulley’s couplings are the best.”
The motor's output shaft is connected to the ball screw shaft by Miki Pulley's "SFC (Metal Plate Spring Coupling)"
Miki Pulley’s strength lies in providing technical solutions tailored to on-site conditions
I really appreciate how they take our on-site circumstances into account and offer a variety of technical solutions. I’ve also heard that
when the product we wanted wasn’t in the catalog, they went out of their way to create a custom coupling with added value just for us.
The primary use of Miki Pulley’s couplings is to connect a motor’s output shaft to a ball screw shaft. Therefore, it’s fair to say that the customer bases of Kuroda Seiko—whose main product is ball screws—and Miki Pulley are nearly identical. In the future, we’d like to exchange technical ideas and realize joint development of new products.
Kuroda Seiko and Miki Pulley have collaborated on joint patent applications in the past, and I believe we are able to undertake such initiatives precisely because we are partners who go beyond the typical user-manufacturer relationship.