304 Stainless Steel Gears for Food Processing Lines

Client Background#

The customer is a food packaging machinery enterprise. Its equipment has to run in a high-cleanliness environment, and the gears in the drive train have to be corrosion-resistant and able to work without grease lubrication, because any lubricant that escapes from the drive can reach the product being handled. Corrosion resistance and cleanability are therefore part of the specification of the gear itself rather than an add-on to the machine.

Requirement & Challenge#

• Material 304 stainless steel, non-standard module M3.5
• Tooth surface roughness Ra ≤ 0.8 μm
• No grease lubrication required, to avoid any risk of contaminating the food
• Corrosion-resistant and easy to clean, so that routine washdown does not damage the working surface

The non-standard module M3.5 means the gear had to be made to the customer’s drawing rather than selected from a standard catalogue, and the dry-running condition had to be solved by the material and the tooth surface rather than by a lubricant. Meeting the material requirement alone would not be enough: a corrosion-resistant gear with a rough flank would still not run smoothly without grease.

Solution & Process#

1. Material selection - 304 stainless steel, corrosion-resistant and non-toxic, which suits both the cleanliness requirement of the line and the washdown regime it is cleaned under.
2. Dry-running design - A special tooth surface treatment reduces the coefficient of friction, so that the gear pair can run without grease lubrication and no lubricant film is needed between the flanks.
3. Precision machining - CNC gear milling followed by gear grinding, which brings the flank to the specified roughness of Ra ≤ 0.8 μm and keeps the tooth geometry within the tolerances of the customer’s drawing.

Result & Feedback#

• No grease lubrication is required, meeting the food hygiene requirements of the line
• The drive runs smoothly, with operating noise below 75 dB

The combination of 304 stainless steel and the specified surface finish covers both sides of the requirement at the same time: corrosion resistance for the environment the machine works in, and a low coefficient of friction for dry running.