The answer to this question is yes, if there is improvement potential, a revisit to the design can happen.
Product improvement is making changes to a product to make it more effective or efficient. This can involve changing a product’s design. Materials, processes or packaging are most common areas to assess for ways to improve upon. When one of UEA’s Rotary Unions and custom swivels is reviewed for product improvement, the aim is usually meant to improve its manufacturability and also it can be to make the product more appealing to our customers.
In this article, I am reflecting on one instance that occurred this past year where rotational torque of one of our customers’ custom swivels was the initial area that was analyzed for potential improvement. Even though we were keeping within our customer’s limit for rotational torque value (generally measured in ft*lbs. force at UEA), we felt that there could be ways to reduce the torque which would equate to less friction when the swivel was in motion. By reducing friction, this would enhance seal performance and longevity of the unit as well as improve future seal kit installations.
The rotational torque of a hydraulic swivel is what is required to overcome the resistance to turning. Below is a list of general concepts that were used as a guide during this project and helped to determine the optimal swivel rotational torque values of this swivel along with notes (in blue) which were used to determine direction:
- There is a “break away” torque value when first starting the rotation in our test stand from a static position.
- This was expected and the test showed that this occurred – no action required.
- After the rotation has begun, the dynamic rotation value should be lower.
- This was expected and occurred. Our goal was then to lower this rotational torque value.
- The friction between the seal and sealing surface creates resistance to turning.
- There was potential for improvement in this area by slightly decreasing the amount of press-fit between the seal and the spool.
- The larger the seal diameter, the higher the resistance to turning.
- By design and space constraints, the seal diameter could not decrease – no action here.
- The more seals, the higher the resistance to turning.
- By design, the number of circuits was defined and could not decrease – no action here.
- The higher the pressure rating within the circuit, the higher the resistance to turning.
- Because of variable operating pressures, potential for changing some seal material specifications around the low-pressure ports would decrease torque values.
- Seal geometry affects resistance to turning.
- This area was reviewed for improvement potential, and thoughts were that if the leading-edge contaminant seal were to increase in size, that would benefit our initial mission as well as improve assembly installation.
- Seal material affects resistance to turning.
- It was determined to change certain seals to a softer material (PTFE) around the low-pressure ports.
- Non-pressurized ports create lowest resistance to turning.
- All ports were pressurized therefore no action here.
- Every other port pressurized creates highest resistance to turning.
- All ports were pressurized so this was not a contributing factor to the resistance scenario.
- All ports pressurized equally crates similar torque to non-pressurized configuration.
- Port pressures varied therefore changing material specification around the low-pressure ports was determined to be the best action to help in reducing rotational torque values.
- Different permutations of pressured ports will create a wide variety of swivel torques.
- By design, the order in which the circuits were located was defined and could not be changed – no action here.
After going through this list and weighing various options for improvement, seal material specifications were changed around the low-pressure ports in this swivel design which created less friction thus helping to reduce rotational torque values, the sealing surface of one set of seal-types was altered slightly which reduced friction between those seals & the spool and the leading-edge contaminant seal increased in size which assists with seal installation and swivel assembly. Furthermore, process improvements were made which will improve the manufacturing of this item.
All of this attention to product improvement on a production item provided an opportunity to work with our customer and it showed them that UEA is dedicated to providing outstanding products as well as it assisted “our own” such as UEA’s manufacturing, assembly and testing teams.
We, at UEA, thrive on building partnerships with all those we work with for the benefit of producing quality products.
Rachel Wiltse, Hydraulic Design Engineer