Ensuring Product Quality Through Incoming Inspections

August 23, 2016

This spring, United Equipment Accessories started completing an incoming inspection on all of our supplied parts. This inspection has helped reduce supplier quality issues on the production line. Reducing supplier quality issues allows the team members to focus directly on how they are building the product, and not worry if the parts they are using are to spec and if they are going to work.

Below shows a graph of the number of supplier non-conformances we are seeing on the line compared to incoming inspection. Some non-conformances are not able to be found until the parts are machined in house – an example would be porosity in a casting.

Non-conform pic

An Incoming inspection process may include one of the following:

  • Visual Check
  • Dimensional (with up-to-date calibrated tools)
  • Documentation Review
  • Checking the Certificate of Compliance

 No matter how controlled a UEA supplier is, all of our supplier’s parts go through our incoming inspection. Finding non-conforming issues when the parts arrive allows us time to get new material in before it’s needed for production. For more information on quality at UEA, check out our blog on PPM reduction here.

Justin Wissler
Quality Technician

How Does a Slip Ring Work

August 16, 2016

We know that slip rings transfer power and data between a stationary and a 360 ° rotating surface.  But how does this happen? How does a slip ring work?

On an elementary level, a slip ring is made up of two main components – a metal ring and a brush contact.  With low speeds of 150 RPM or less it makes no difference if the rings rotate and the brushes are stationary or if the brushes rotate and the rings remain stationary.  The number of rings and brushes found in a slip ring assembly vary depending on the needs of the device.  Additional combinations of rings and brushes are stacked along the shaft or axis of the slip ring.  Many slip rings are contained within housings to protect them from dust, moisture and other elements that may cause it to malfunction.

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UEA brush contacts, which are always in pairs, are made of sintered metal copper graphite or silver graphite and rub against the outside of the rotating metal ring.  They maintain a continuous electrical connection as one portion of the assembly rotates.   The brushes are riveted to nylon arms and allowed to pivot at the rivet.  The brush arms will also pivot on the brush posts.  With both the brushes and arms allowed to rotate, complete contact at all times between the ring and brushes is assured.  Although typically one brush pair per ring, amperage requirements may necessitate the use of four or even more pairs per circuit.

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The ring is made of electrically conductive metal, usually brass, but it can also be plated silver or coin silver, and is usually mounted on, but insulated from, a center shaft.  The insulating material between the rings and between the ring and the shaft is made of nylon, phenolic plastic or another non-conductive material.  As the ring turns, the electric current is conducted through the brush to the ring making connection.

The wire leads from the brushes and from the rings are connected to electrical circuits.

This is how a slip ring works.

If you have any questions, please give us a call at 1-800-934-9986. Interested in learning more? Another article you may be interested in is, “Can One Slip Ring Assembly Handle Both Power and Communication?

Wanda Steffen
Design Tech

How Does the Custom Hydraulic Swivel Process Work?

August 9, 2016

When a hydraulic swivel is needed, many applications require a custom hydraulic swivel be designed and built. We thought we would take some time to explain how the process of designing a custom hydraulic swivel works.

Designing a custom hydraulic swivel begins with communication between the client and the design engineer collecting information and asking questions.  The client needs to provide general information such as number of ports, size of each port, the location and position of each port on the housing and spool, the operating pressure, and the function of each port.

Further discussion should be covered regarding the flow rate and the line velocity requirements of each port. Other points of concern are:

  • How is the swivel to be assembled into the client’s equipment?
  • Where is the torque arm located in respect to the mounting flange on the swivel?
  • Can the mounting flange be welded to the housing or bolted?
  • Is the swivel painted? If so, what’s the paint specification?
  • If there is a slip ring included, what size of through hole is needed to pass through the wiring harness and connectors?
  • Is the slip ring located above or below the swivel?

All of the collected information is then written up into a request for a quote.

The design engineer takes this information from the RFQ and begins the design layout process of the spool. The size of the through hole for the slip ring wiring harness and connectors needs to be determined and is located at the center of the swivel. The location of each port is laid out according to the client’s request. The size of each hydraulic circuit is designed to accept a certain flow rate using the recommended pressure line velocity of 25 ft/sec and the return line velocity of 10 ft/sec; unless otherwise specified by the client.

The flow rate, line velocity and hole size all have an effect on the port size for each circuit. The area of each flow groove around the spool is 1.5x that of the deep drill. Care must be taken to provide enough wall thickness between the bottom of the flow grooves and the edge of each deep drill to maintain a 4:1 safety factor. The wall thickness is determined by the operating pressure of each circuit.

The sum of all the circuit holes and flow grooves determines the bore size of a swivel. The bore size determines if the cap seals are located in the housing or in the spool. For swivels with smaller bores, the cap seals are located in the spool and the flow groove can be located in the housing or shared between the housing and spool. Swivels with larger bores the cap seals are located in the housing and the flow groove can be located in the spool or shared between the spool and housing. The preference is for the seals to be located in the housing.

It is preferred that the location of the low pressure circuits be at the ends of the swivel with the high pressure circuits positioned inboard. An energizer and cap seal are located between each circuit. If a high pressure circuit is located at the end of the swivel, a weep needs to be provided and connected to the return line back to the tank. The wear ring is the bearing element of the swivel and prevents contact between the housing and spool. The purpose of U-Cup seal is to contain and prevent hydraulic fluids from exiting the swivel. At each end, and internal to the swivel, are the excluder seals which keep particulate from entering the swivel. External to the swivel, and at each end, we have a thrust washer and o-ring. The o-ring prevents the larger contaminates from entering the swivel and the thrust washer prevents metal contact between the housing and spool.

The housing is usually rigidly mounted while the spool is allowed to float within the housing while its rotation is constrained. The torque arm controls the rotation of the spool. When the mounting flange is welded onto the housing, the material is steel tubing; and when the mounting flange is bolted to the housing we can use ductile iron trepanned tube.

If there is a slip ring, we prefer it be mounted above the swivel. If it’s located below, then a liquid tight connector needs to be added at the top of the swivel to prevent moisture from getting down into the slip ring.

This is how the flow of the custom hydraulic swivel process works.

To help determine if your application needs a custom hydraulic swivel, read our article, “Do I Need a Custom Hydraulic Swivel?” If you have any questions about this topic, give us a call at 1-877-394-9986 and one of our Hydraulic Swivel Engineers would be happy to answer any question you have.

Tom Van Veldhuizen

Reducing Slip Ring Enclosure Size

August 2, 2016

Recently, some of our customers have been asking, “What can be done to reduce the overall height in our S15A series slip rings?” Typically these slip rings are designed to mount above or below our customer’s existing hydraulic swivel. Most of the time, the outer portion of the slip ring is retained by a fork style mounting bracket coming from the hydraulic swivel. The fork style mounting bracket catches a bolt or pin which threads into the side of the slip ring base casting for retention.

In the case that the hydraulic swivel is not a UEA design, changing the fork bracket design is not a cost effective solution for the customer. We are able to work around this and maintain the same retention method with the use of our S15D series slip ring. In switching to the S15D series, the elbow liquid tight connectors for the brush harness exits need to change to straight liquid tight connectors, which allow the mounting tube flange to be pulled up closer to the bottom of the base casting. The threaded torque hole in the S15A series is moved up into the side of the dished base casting of the S15D series the same distance the mounting tube flange is moved, keeping the distance for the fork bracket to pin retention the same. In the particular example shown below, we were able to reduce the overall height by two inches while maintaining the same mounting method for the customer.

Reducing Slip Ring Enclosure Size

Reducing Slip Ring Enclosure Size

In any case, we customize our slip rings as much as possible to meet the needs of our customers. If you would like to learn more about UEA slip rings visit http://www.uea-inc.com/products/slip-rings or give us a call to talk about reducing your overall slip ring size.

Josh Bockholt
Sr. Designer Engineering

Do I Need a Custom Hydraulic Swivel?

July 26, 2016

While searching for hydraulic swivels a quick peruse through the internet will yield many seemingly fruitful results.  Many of the companies that offer hydraulic swivels have attractive looking websites.  A global marketplace almost mandates companies present slick looking graphics for viewers to admire.  The quest for a hydraulic swivel and/or slip ring brought you to the website, but what is it that gets you to take the next step?  The next step usually depends on the type of customer that you are.

Every customer is unique, but we can classify many of the potential customers into groups.  The first group are the customers who require a simple swivel for a custom assembly, usually they are able to modify the larger assembly to accommodate a cost effective solution.  These customers are apt to pick an ‘off the shelf’ style unit, as availability and cost is a considerable driving factor.

Another group of potential customers use an existing swivel, but for one reason or another, are looking for a new supplier.  Price and availability are important to these customers, but also intangibles like customer service and commercial considerations as well as other unique requirements.

The last group are folks looking to develop a custom swivel for a new project they are working on.  These individuals encompass all the previous requirements as well as additional engineering resources needed to develop a custom design suited specifically for their requirements.

UEA employees strive to embody our company motto ‘solving challenges from the inside out’.  We are available to answer any questions you may have even before you consider requesting a quote.  As you can tell by our motto, UEA is built to serve your design challenges.  We will solve your problems by supplying custom designed and built hydraulic swivels and/or slip rings.  If you would like to request a quote, do so here. If you would like to have a conversation with myself (Brady) or one of our other Hydraulic Swivel Engineers to discuss whether or not a custom or standard hydraulic swivel is necessary, call us at 1-800-394-9986 and ask for Brady or a Hydraulic Swivel Engineer if I’m not available.

Brady Haugo
Sr. Design Engineer