Hello, I’m Morio!  This summer is forecasted to be very hot. Everybody, take care of yourself and stay healthy!

Today, I would like to explain the role and quality points of the “key” in the feed shaft of our machines. A “key” is a small part that connects a rotating shaft to a rotating component, aiding in the transmission of torque. In terms of product quality, especially for important feed shafts, the “key” is generally used in the following two places:

A: The parts where the gears from the motor (drive unit) connect to the feed shaft. This is where the rotation starts.
B: The parts at the end of the feed shafts where the feed rollers (processing tools) are attached.

There are various shapes of keys, including square, convex, and other special forms, which vary in dimensions between the shaft side and the component side.

Roles of the Key

1.Torque Transmission:
The key efficiently transmits the torque generated by the motor or other power sources through the shaft to other components (in this case, the feed roller). If the key does not function properly, slippage can occur between components, causing the machinery to malfunction.

2.Positioning:
The key also plays a role in ensuring that the attached components are held in the correct position. This ensures the precision and repeatability of the machine’s operation.

3. Ease of Installation and Removal:
Using a key allows gears to be easily mounted on the shaft and removed as needed. This facilitates maintenance, repairs, and the replacement of the feed rollers.
However, ease of removal does not always mean “better”. Please refer to the following for more details.

Quality Points and Our Commitments

1. Material and Design:
Keys are made from high-quality steel or alloy steel to withstand wear and breakage because they require resistance to abrasion and strength. Of course, the design of the key and the keyway must be appropriately selected based on the characteristics and load conditions of the machinery being used. Using the wrong type of key can increase the risk of performance deficiencies and failures. For example, the number of keys on a shaft can dictate not only the material used but also detailed designs such as heat treatment methods, load distribution, and prevention of misalignment.

2.Dimensional Accuracy and Assembly Techniques:
The presence of a key also means there is a keyway on the shaft side, and the dimensional accuracy of this keyway is crucial. Inaccurate dimensions can lead to poor fit of the key, reducing torque transmission capacity and causing excessive wear or damage. While we generally use key materials that meet the new JIS standards, the load conditions at specific locations, especially where the load changes in size and direction frequently, may lead to premature wear or play in the fitting.
At our company, we manage dimensions to tighter tolerances than JIS standards, using custom-ordered key materials and controlling dimensions with 1/100mm range.During the machining of parts, finishing is often done before heat treatment. However, to prevent any deformation due to the heat treatment, we ask our partner suppliers to perform the final finishing after the heat treatment (Of course, the parts become harder and more difficult to be processed.). So they use diamond end mills or electrical discharge machining to meet our request..

By the way, every autumn, we host a BBQ party in our company parking lot and invite our partner companies. They often say with a smile that “working with Shinko’s parts is much more challenging than other customers’ parts!” This BBQ is a special occasion where our employees cook meat and serve homemade dishes. Our partners look forward to the party, often bringing their families along. I’m really looking forward to working hard this fall too!

Furthermore, during assembly, each piece is adjusted with 1/1000mm range. The key side is made slightly larger to ensure a tight fit, and the finishing of the contact surfaces is crucial, performed with machines for smoothness without irregularities, with slight differences in the finish between the deeper and more superficial parts of the fit. Such detailed finishing and fitting require high-level assembly skills.

The feed rollers, being replaceable parts depending on the wire diameter in spring making, do not need as strong a fit as the gear parts, but there can be feedback from customers about difficulty in fitting. I personally struggled to remove a slightly misaligned feed roller during my training, a tough lesson in the precision and durability we aim for in our designs.

I hope this detailed explanation helps you understand the critical role and intricate details involved in designing and manufacturing the key components of our machinery.

Stay tuned and Look forward to my next blog!