WireProcess Specialties

USCAR-21 is the quality standard that can strike fear into companies who deal with automobile assembly companies.  USCAR-21 is a universal standard which applies to suppliers of electrical assemblies to The Ford Motor Company, General Motors Corporation and Fiat Chrysler Automobiles.

Companies who are not involved with automotive wire harnessing can quickly dismiss this standard as not applicable to their business and industry. Although this is true, some of the components of USCAR-21 are valuable and can be directly applied to the validation of wire terminations for any industry. Companies not considering some of the key features of USCAR21 can miss out on the benefits to quality improvement.

We will drill down to reach those best practices which can be applied to your company.

Prior to the formation of USCAR-21, each automobile manufacturer had their own testing and validation standards. The adoption of a common standard meant more efficiency in the testing process, especially for suppliers who provided wire harness across a number of automobile OEM’s listed..

The USCAR-21 standard includes mechanical and accelerated environmental tests which are designed to duplicate potential operating conditions a wire to terminal connection can experience through the expected life cycle of an automobile. Demands on the electrical system are increasing with smaller wires carrying communication signals and larger wires used in current load in applications such as EV batteries. A comprehensive standard was required to address the performance requirements through the full range of harness size and complexity. At the same time, to reduce some of the bureaucratic burden from the supplier end.

Lets bring USCAR-21 down to it’s most basic objective: Electrical connections must maintain low electrical resistance through the expected life span of an automobile. This is achieved by adhering to critical crimp design and validation criteria.

Ultimately, monitoring the crimp process during production is important to ensure specifications from the validation stage are maintained.

Here are a few considerations to the actual electrical crimp.

• The terminal supplier’s recommended crimp height and width is the starting point of all initial and pre-production crimp validation. Wire terminations should perform acceptably though the tolerance range of the recommended terminal crimp height.
• Crimp compression, the process of encapsulating the wire into a crimp barrel with sufficient force to deform the strands from their round shape is a major factor in acceptable electrical resistance. Compaction of the strands by 15 to 20% provides the best opportunity to pass electrical resistance testing. There is a direct correlation between the amount of wire strand compression and electrical resistance. Especially leading up to and through the above compression range.
• Crimp barrel and wire size must be carefully matched to ensure the optimal compression is achieved. In combination with the proper crimp tool design. Factors indicating a poor wire to terminal match:
  • Wire strands under-compressed.
  • Strands not evenly distributed in the crimp barrel
  • Crimp wings curl and touch the bottom (floor) or sides of the crimp barrel.
  • Crimp wings with a gap at the top, with strands not fully encapsulated in the crimp or pressed on top during the crimp process.

Cross Section showing under compressed strands and voids.

• Serrations in the crimp are designed to break oxides present on the surface of wire strands, providing better electrical connection. Also to assist in the mechanical secure-ness of the crimp.

Consideration of measurement methods.

• Crimp Height is the primary test factor in a validation and in-process measurement.

• Tensile (Pull) testing is a secondary testing method to ensure the wire termination has “sufficient mechanical strength”. It is not a determining factor of electrical performance as low or high compression can affect not only mechanical but electrical performance.
  • In all cases, insulation support on terminal crimps must be peeled back or not crimped at all for pull testing. Pull test readings should be made on the wire to terminal crimp only.

• Crimp Cross Section un-covers the actual crimp condition from wire/terminal match and crimp tool profile. As well, crimp applicator setup can be checked (i.e.: terminal feed position).

• Visual inspection criteria ensures the proper machine setup provides the best crimp. Visual factors of an acceptable crimp are:
  • End of wire protruding on the contact side of the wire crimp. Known as brush.
  • Insulation and wire (roughly 50:50) present in the “window” between the wire and insulation crimp.
  • Bell mouth present on insulation side of the wire crimp to protect wire stands. Bell mouth can also be present on the contact side of the wire crimp.
  • Insulation crimp wings should not penetrate the insulation and make contact with the internal stranding and should fully encapsulate the insulation.

Electrical and Electronic devices that are not assembled into an automobile will have their own performance parameters. In most cases they are not subject to temperature and humidity fluctuations that are present in an automobile. But totally dismissing good crimping practices and not applying some of these best practices can expose your products to premature failure which carries a high cost (and liability). That’s the important factor when Acting on the Cost of Quality, understanding the Benefits and avoiding the risks of Inaction.

WireProcess is equipped and ready to deploy the tools you need to take your crimp process to the next level. Connect Your Way to WPS.

Every Decision has a cost.

This is the third and final part of our series Counting the Cost of Quality. In Part One, we discussed The Cost of Action, those decisions that are made on the basis of acting on information that has been provided. In Part Two, The Cost of Inaction covers the implications of not acting. Part Three will cover the Benefits.

As a company with a bias towards action, we consider the benefits of action far surpass the benefits of not acting. But acting after thoughtful analysis of the decision being considered. We acknowledge that any decision even a decision to act, carries some risk. Decision paralysis can take hold when the fear of making a decision is greater than not acting, part of the reason the cost of inaction can be high. We can consider as many variables as possible but there will never be enough information to completely mitigate risk from a decision.

So to consider the benefits of making a decision to act, let’s use an example of acquiring a Crimp Cross Section Lab to enhance your company’s quality process validation and monitoring capability. You have considered the upfront cost which includes the actual cost of acquisition, employee training and integration of this system into the company infrastructure. Consider the benefits which can apply to this decision:

Internally, individual employees directly involved with the new acquisition will be happy to see the company has provided new tools to help in their day to day work. As a collective, employees feel a higher sense of security that the company is investing in the company’s future.

As a company, new tools that are used can improve the overall quality of output. In the case of quality validation like our example, this provides a measurement tool to track the quality of output. Any tool to measure progress is critical (and may I say essential) to a company’s survival never mind growth.

Externally, existing customers will have a higher chance to keep existing business with your company when they see investment in infrastructure. Investments that can benefit them. And provide new opportunities to grow the business relationship through added contracts as they come up.

Potential customers will be more driven to work with you as they see investment in new infrastructure. In some cases, new processing or validating tools (like Cross Section Analysis as described) are minimum gateways to a business relationship even starting. For others, they will see your company set apart from your competition as internal investment in hard processing systems (capital) and training (human resources) are made. Where the investment is emerging and state of the art, you separate yourself from others who have not advanced as far as your company has.

These are just a few benefits to making the investment to improve quality. I am sure there are other direct and indirect benefits not mentioned.

This series was created to illustrate the opposing sides of a decision, to act on a decision or to stay the course (which in and off itself is a decision). You may not be in a position to be part of the decision making process of the company you are currently employed with. But regardless, you will be affected by any decision (or non decision) made.

In a perfect world all companies will err on the side of action and see the positive aspects of acting to improve the company. But some will stay the course and not act. And may not see any difference in the short term. The same with an action decision, there may not be a positive result in the short term. But the difference will lie in the long term implications. And if I were to consider the long term survival prospects of any company, the bias toward making positive action on decisions would make me more confident in that company’s future. Certainly that is the goal for our company.

WireProcess Specialties has many decades of experience in processing and validating technology for wire processing. We are here to help in making the right decision. Connect Your Way to start the dialog.

There I said it. Let me repeat:

Crimp Force Monitors Do Not Solve your Quality Problems.

Now that it’s out there let’s back up a little. First of all, let me be crystal clear. Crimp Force Monitors (CFM) are an essential tool of a quality system for any company that is serious about providing quality wire assemblies. The ability to monitor your process with a crimp monitor is extremely valuable for a number of reasons which we will unpack in this article. But let’s put things into their proper perspective.

First of all, a crimp process that has excess variation exists that way with or without a CFM. A CFM does not resolve crimp problems but will provide plenty of notification to the operator of this condition. In the form of CFM alarms. It is what is done from this point that is critical.  If the tolerance is opened up to silence the alarms or (worse) the monitor is turned off, then the true value of the CFM is lost.

Second, a CFM works best with a process that is in control and shows little piece to piece variation. This provides sufficient room for detecting small defects in the crimp process. Excess variation adds “noise” to the detection process and a CFM will have a harder time in determining a defect or just normal process variation.

The video below is from the 2016 Electrical Wire Processing Technology Expo and the seminar co-sponsored by C&S Technologies and Applitek Technologies: Do You Really Know Your Crimp Process where we discuss the CFM Cycle, a scenario played out countless times as new CFM Technology is introduced.

So what value is a CFM in the crimping process?

First, real time monitoring is 100% effective in measuring the crimp process. Visual inspection is only 80% effective over time and 100% manual inspection is not practical. It also answers the question: “what is happening between the first off article inspection and spot in process inspection”.

Second, as a process analysis tool, a CFM is effective in improving the crimp process over time. This is done by analyzing the five elements of a terminal crimp. And improving each process. The direct effect is a process in greater control and able to detect smaller variation.

Finally, as part of an integrated network of processing machines, the CFM can feed valuable production quality data into a central database for archival and analysis. Also provide a level of production quality approval by preventing access to production equipment until quality measurements are within allowable parameters.

So the question is “Do you need a CFM equipped facility?” Consider the following and judge for yourself.

• Pull test and crimp height measurements are a static and one-time check of quality parameters. As important as they are to production quality, they are not sufficient in of themselves. A CFM is one example of dynamic quality measurement in real time. Press Analysis is another example of dynamic measurement.
• CFM’s remove subjective judgement of good or bad crimps from employees.
• CFM’s monitor the whole crimp process and the associated elements.
• Without crimp monitors, the risk of defective wire harnesses increases and the cost of rework (not to mention product liability) will exceed the initial investment of crimp monitor technology by a large margin. “It hasn’t happened to us so far” you may say. “We have crimped millions of parts over the years with no problem” is another one. The laws of probability will eventually catch up without effective dynamic crimp monitoring. Why take the risk?

Do not take the risk! Our Global Technology Partner: Crimping and Stamping Technologies is a global authority in the terminal crimp process. Connect Your Way to WPS for an analysis of your crimp quality requirements.