Tag Archive for Crimp Quality

What can other industries learn from Automotive standard USCAR21?

USCAR21 Title

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 (130)

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.longitudinal cross section 5

Consideration of measurement methods.

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

CHT Mic

  • 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.WhatsApp Image 2016-11-10 at 9.31.28 AM
    • 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.

WhatsApp Image 2016-11-10 at 9.33.24 AM

  • 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).

cross-section-273

  • 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.

Counting the Cost of Quality: The Benefits

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.

Counting the Cost of Quality: The Cost of Inaction 

Every Decision has a cost.

Continuing the series Counting the Cost of Quality,  we turn from the Cost of Action in Part One to the Cost of Inaction.

So what happens when you do not act? Maintain the status quo.  I acknowledge that there are some times in a company’s history when a short term “pause” is needed. Due to uncertain economics or other external conditions. This is different from big picture inaction. In the case of quality, there is no time that a company should pause from improving quality, quality systems or understanding the changing dynamics of quality processes.

… there is no time that a company should pause from improving quality, quality systems or understanding the changing dynamics of quality processes.

In the end all decisions to act or not rest with management. And the implications of the decision (or non decision). Here are a few possible considerations and implications of not acting.

First, not taking the step of understanding the changes in quality processes and the standards that industries are using to validate and monitor quality. This can be as damaging as knowing and not acting.

Some industries are leaders in quality. And what they adopt often become best practices which other industries adopt in whole or in part. They were created for a reason. Not investigating new practices and reviewing the potential use in your organization can be a lost opportunity to become a leader in your industry. For example the Automobile Industry are widely using cross section analysis to validate, monitor and improve quality of connector crimping. With the cost of these systems coming down, it makes sense for non-automotive companies to start adopting cross section analysis.

Not investigating new practices and reviewing the potential use in your organization can be a lost opportunity to become a leader in your industry.

What if your competitor seized the opportunity to implement new quality processes? And their quality improved when they used these new tools. And they broadly publish their new capability to the world. Prompting companies (including your customers) to take notice. You are at a strategic disadvantage when your competitor gets a jump on your company.

You are at a strategic disadvantage when your competitor gets a jump on your company.

Inaction due to the cost of processing tools, systems and training ignores the long term benefit from reduced cost of processing. Scrap and rework costs can eat into profitability. A focus on quality improvement can also help to improve production efficiency.

Employees are watching. Engaging personnel in the process of quality improvement can be positive and beneficial. But when personnel see management not acting, they soon follow and productivity declines. Personnel on the factory floor are looking for individual benefit in the case of working conditions and some level of assurance the company is going all out in their efforts to maintain and grow the business.

Customers are also watching. With domestic and international competitors on your customer’s doorstep, can you afford to not consider new quality systems? And implement them into the company’s culture.

With domestic and international competitors on your customer’s doorstep, can you afford not to consider new quality systems?

Looking at the negative side of this topic is something companies do not enjoy doing. Simply put, ignoring the world changing around you or knowing and not acting is not a good business strategy. And can be damaging or fatal to a company in the long term.

The good news there is always an opportunity to turn the ship around, no matter how big the ship. Today would be a good day to seize the opportunity and start acting!

 

Counting The Cost of Quality: The Cost of Action 

Every decision has a cost.

Large or small there is a cost to every decision. Of course there is a sliding scale of the size of a decision and it’s relationship to the overall implications to the organization. Some costs are economic and some are not.  Deciding on a bathroom cleaner or brand of pencil to stock have fewer implications than a capital purchase or facility relocation.

This the first of three articles focused focused on quality and considerations when making improvements to an existing system or completely starting from scratch. Also the costs associated with these actions that have far reaching implications to product quality within a manufacturing environment. In this post we are focusing on the cost of action.

Here are a few point for consideration.

Management acts on quality improvement but there is usually a trigger. Triggers that cause management to act are either external or strategic. External triggers often come from customers who require improvement in quality either due to a complaint or issue. They are also driven by the customer’s desire to focus on a specific industry sector that demands higher quality standards. Strategic triggers are based on the company moving into a new industry sector which (like the customer) demands an enhanced quality or documentation of quality. Regardless of the trigger it all boils down to one thing: economics. Losing a key account or losing out on a new opportunity to grow the business in a new direction can greatly affect revenue which can affect the business partly in the short term but mainly in the long term.

Management not only needs to be fully committed to a new quality system, they need to be the champions of it. Often it is management that has a neutral or “wait and see” attitude. This can be damaging to the success of implementing a new quality system. Or the efforts to make permanent the change in culture. Employees are watching. When management waivers, employees often follow.

We will expand on the potential negative affects in part two: The Cost of Inaction.

Commitment includes attention to the following areas:

Employees need to be fully supported. In the form of solid two communication between management and employees. They need to understand the reasons behind the change or initiative. When communication breaks down so does the trust.

Employees also need appropriate training. The company needs to provide the funding for training (and re-training) for all workers directly (and indirectly) involved in quality.

Resources are critical to the success. These include measurement and in process monitoring tools for validating and monitoring production. Also access to applicable quality standards for your industry. These tools provide data necessary to feed back to management on the current state of the quality system.  And levels of improvement over time. One important point. Providing new measurement tools is an important first step but often they uncover the current state of the quality system. They do not improve it. Training in conjunction with the above tools can provide the information needed to make the changes needed to drive quality improvements. But looping back to management’s commitment, they need to drive the changes needed (and the speed of change) and support the organization as a whole.

Capital Costs are important over the life of a quality improvement initiative.  As information starts flowing on the current capability of the production system, it may become evident that production equipment over the long term is not capable of repeatable results of a higher quality level. Replacement production equipment or major upgrades to existing equipment will be necessary.

In summary, making a decision to improve quality comes at a cost. In the attitude of management and employees, a commitment to invest in the resources and the capital needed to make an improvement in product quality. There is also a cost of inaction which we will cover in part two. And the benefits? Part three will uncover the reasons why sticking it out to the end will be critical to the company’s survival in rapidly changing business conditions.

Crimp Force Monitors Do Not Solve Your Crimping Problems

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.

Static vs Dynamic Measurement of Crimp Elements

Quality measurement has been an essential part of process validation and control for manufacturing for centuries. Engineering a product design with critical dimensions needs to be validated by quality measurements during the production cycle.

In the early 20th century, statistical analysis of quality was introduced into the quality process of validating manufactured goods and adopted in a number of industries. Automobile production embraced statistical analysis as a result of W Edwards Deming’s influence as the founding president of the American Society for Quality Control.

Today in many industries, a mix of static (one time) and dynamic measurements are used to validate process measurement. In the Wire Process Industry there are a number of measurement tools used which include pull testers, crimp height micrometers and dynamic validation tools such as crimp force monitors. In Wire Processing, dynamic measurement tools are being adopted, aided by the inclusion of them in new processing equipment. But in some respects, a general awareness of the critical nature of dynamic always on quality measurement tools is lacking.

For example, crimp height measurement. Some companies still use the crimp height as a static first off quality measurement and then not measure another part through the balance of the production run.

Or Press Calibration. Calibrating a crimp press with a shut height gauge to the proper shut height without measuring shut height or press force repeat-ability.

These are mistakes. A single part only assures you that that part (or process) is within production tolerances. And does not take into account variation from all input elements in a crimp process.

Dynamic measurement tools provide a piece by piece indication of process capability and detection of crimp errors. Dynamic capability studies of press shut height and crimp force provide valuable information on a press’ ability to supply repeatable crimp force.

PAL_600 rev

Press Analyzer

Here is a clip from our seminar at the 2016 Electrical Wire Processing Technology Expo. This clip illustrates the value of dynamic press analysis.

Static measurements such as crimp height and pull test are not obsolete in today’s production environment. In fact they are valuable first off process validation tools but need to be supported by dynamic measurement from crimp force monitors and crimp camera systems.

MX

MX Series Crimp Force Monitor

So what are the implications of not dynamically measuring crimp elements in real time?

  • Rework cost from defective product
  • Related costs and penalties from customers
  • Lower customer confidence
  • Maintenance and Quality resources not deployed on priority issues because objective information is not available.

Flip these around and you can see the benefit to your organization. So you say these problems have not occurred to our company? Perhaps not in the past but there is always a real risk of these problems coming up in the future.  And without objective analysis, you just don’t know.

Act now. Let us provide you with the tools and services you need to get a start on measuring and improving your crimp quality. Connect Your Way to the WireProcess Global Community.

 

You Asked: Frequency of Cross Section Analysis

A customer asked this question during a crimp training session I was performing: What Frequency should you perform Cross Section Analysis on a specific wire and terminal combination?

I will provide a response to this question shortly.  But you need to understand the uses of Cross Section Analysis. And how it applies go the crimping process in general and specifically how it applies to your company.

For those who are new to this technology, a crimp cross section is an image of the inside of a terminated wire. This image shows the result of how the five elements of the terminal crimp process come together.  Valuable information can be pulled from this image. For a more detailed explanation, please read our post Terminal Cross Sectioning: Taking a Peek Inside.

I consider Cross Section Analysis as the Swiss Army Knife of Crimp Quality.  A Cross Section can serve many purposes. First as a base line master image of your crimp process in the initial production phase. This is a report that can be retained for future analysis or provided to a customer for their quality audit purposes.

Second, knowing the basic crimp configuration will provide an indication of how the crimp will perform. If the wire and terminal combination are specified and the crimp height is established by the terminal supplier then what you see in the cross section image is generally how the crimp will look through the crimp process. If the crimp wings are touching (or close to touching) the internal crimp walls or floor, this can cause crimp monitor alarms. Or if crimp wings are forming but not capturing stranding (uneven distribution), this is a sign the crimp could perform poorly in electrical testing or in use in the device it is installed into.

cross section (110)

Crimp Wings Touching the floor of the crimp.

cross section (130)

Under Compressed Crimp

Next, in process validation. Comparing the current image to the master image previously captured. Checking to see if crimp tool wear or other inconsistencies have caused the crimp profile to change.

Finally as a process improvement tool. When crimp elements come together, the process capability is the sum of these elements. Improving any of the elements (press, applicator, wire, terminal, operator/automation system) can improve the overall process. And that results in a better terminated wire.

So coming back to the frequency of cross section analysis, an initial image is important as a base line review of the crimp profile. Where there are crimp problems (crimp monitor “false alarms, customer complaints etc..) a crimp cross section helps to determine in process issues. This would be done on an as needed basis. In process image capture to compare the current image with the master image would depend on the overall volume of that crimp. Also consider any changes in the elements of the crimp process. For example crimp tool changes or wear or an introduction of a new wire supplier. Even as simple as an applicator removal and re installation at a later date can be a factor in variation.

There are no established guidelines on the frequency of cross section analysis other than what a customer may establish. But the use of cross section analysis as a validation, in process inspection and process improvement tool will only increase in the future. And why not? The information from this analysis can lead to a better quality electrical connection and a lower risk of failed electrical circuits from faulty electrical connections.

Global Technology Partners of WireProcess are industry experts in their areas of support to the wire processing industry. C&S Technologies are globally recognized for their expertise in crimp quality. For more information, visit our C&S site and our Cross Section Services page. Connect Your Way to WPS.

 

 

Terminal Cross Sectioning: Taking a Peak Inside

Terminal Cross Sectioning is a quality validation technique that is not new to Wire Processing. The use of cross sectioning has broadened over the past few years and cross section systems are now appearing outside of the quality lab and on the factory floor. This trend is expected to continue in the coming years. Cross section labs are expected to be as commonplace as a pull tester in most processing facilities.

In the past, quality tests of a terminal crimp were performed by only a pull tester and being a destructive test, it was a first off and spot in process inspection.  But it certainly did not take into account the inherent process variation of the crimp process itself. Later on as electrical performance demands increased, it was necessary to improve the quality inspection processes. At the same time, crimp design advanced and no longer was just pull test sufficient. Enter crimp compression.  Crimp compression standards were a result of studies into crimping and it was determined that a predictable percentage of crimp compression was needed to assure optimal electrical performance. Crimp Height is based on optimum compression of the wire during the crimp process.

With Cross Section analysis, we can now peak inside the crimp. This cross section analysis provides us with a great amount of detail into not only the materials (wire and terminals), but how they are crimped together.  Information that is used for documentation and archival purposes.  An important aspect of cross section analysis is process improvement. Some of the measurements available from cross sectioning a crimp include:

  • Crimp Height
  • Crimp Width
  • Crimp Compression
  • Crimp Height to Crimp Width ratio
  • Capability Studies including crimp height.

Process Improvement is a necessary component of any company who wishes to reduce their processing costs (material waste and processing time) as well as improving overall productivity. Cross Section analysis can be a valuable tool in process improvement. For example, crimp monitor alarms. Crimp monitors signal an alarm when an element of crimp quality causes excess variation.  Often the suspect parts appear normal and acceptable. Production continues. Later on another alarm occurs.  Same condition.  Parameters are opened up and production continues without alarms. But the underlying problem still exists. Once this cycle starts, the monitoring system becomes less sensitive and at some point only gross errors can be detected.  And the risk of accepting defective parts also increases.

Cross Sectioning a crimp offers one way of detecting an issue that could be quickly assessed and a resolution put in place. See the illustrations below.

cross section (110)

Crimp wings touching crimp floor.

cross section (130)

Uncompressed strands and uneven strand distribution.

These are two examples of conditions which can cause variation which a crimp monitor interprets as a defect. Which can affect electrical performance.

Embracing Cross Section Analysis as a critical validation tool is important for companies in the future. Costs have come down to the point where most companies can justify a base system for plant deployment. The WPS Cross Section Service is another way to get your analysis completed while working out the deployment of system for internal use.

Connect Your Way to WPS.

Quality Connections: The Five Elements of a Terminal Crimp.

The process of crimping a wire to a terminal is a time tested electrical connection method. But gone are the days of a crimp being processed using low grade wire strippers and crimp tools. A wire lead requires tools and processes which are highly accurate and repeatable. A quality improvement process identifies the processing inputs that are used in an assembly.  A baseline quality level is created and the company works to improve the overall process over time.

The quality of a crimp is the sum total of the process capability of five elements in the crimp process: Wire, Terminal, Crimp Press, Crimp Tooling and Operator.

To improve the overall quality, each individual element must be studied and improved. This article will outline some of the aspects of each element which can cause a less than desirable capability which in turn can affect the overall crimp quality. Also we will cover some of the typical tools used to assess and monitor the whole crimp process. This article deals with the crimp process for terminals on a reel but can equally apply to loose piece terminals.

The Five Elements of the Terminal Crimp Process

Wire.

The wire is one of the material elements of a terminal crimp. Typically process variation from the wire comes from a few external sources but mainly downstream processing steps leading up to the operator presenting the wire to the terminal for crimping.

Overall wire quality is an external source of process varitiation.

  • Does the supplier have the necessary quality systems in place to reduce process variation? This includes:
    • individual wire strands
    • overall wire inside diameter
    • insulation material (consistency and overall outside diameter)

Changing wire suppliers or improving material quality can reduce variation.

Downstream processes can impact process variation.

  • Wire stripping and handling:
    • Manual wire stripping or incorrectly adjusted wire processing machines. Correct strip length or piece by piece variation.
    • Blade Condition: cut strands
    • Wire ends frayed from handling. Semi-stripped wire reduces damage to the stripped end of a wire.

Terminal.

The other material element of the terminal crimp is the terminal itself. Like wire, supplier selection and supplier process controls are critical. External factors (supplier side) affecting process variation from the terminal and packaging include:

  • crimp (wire and insulation) barrels. Straight or misaligned
  • terminals feeding straight on the terminal strip.
    • can affect loading position in crimp applicator
  • packaging (reel and carton) protecting the terminals from damage from handling and de-reeling.

The selection of the proper wire range to match the terminal crimp sections is very critical. Terminal manufacturers design the geometry of a crimp to match the wire size. This includes the wire and insulation crimp sections. Mismatched terminal to the wire (gauge and insulation OD) is a major cause of process variiation.

Crimp Tooling.

The crimp tooling includes the crimp punch and anvils as well as the feeding mechanism (the applicator). Some of the major factors in process variation are:

  • worn crimp tooling
  • feed track not adjusted properly, causing terminals not to feed straight.
  • wire stop too far forward or backward. Or excess play in the wire stop itself. Causing variation in target position of the wire to the terminal. Failures are typically high insulation (insulation crimped in the wire crimp), low insulation (insulation not fully captured in the insulation crimp). Or inconsistent piece to piece variation.

Crimp Press.

The crimp press is the one processing tool which typically receives the least attention. Even if all of the above (wire, terminal and crimp tooling) are in control, press wear can cause excess variation. Wear on the crank or casting of the press can cause the press shut height and crimp forces to vary. This can create piece to piece variation. In excessive cases of wear, crimp height and pull test can go out of specification which can cause failure of the electrical connection.

Operator.

The operator is the final element of the five. The operator can cause variation due to improper loading of the wire to the applicator and not monitoring the inbound de-reeling of the terminals from the reel, through the applicator to the crimp tool. The operator can check the terminated parts and without controls in place has the power to accept rejected parts. Or not fully inspecting the batch of wires that have been processed. In the case of an automated machine where the wire placement is handled by a robotic arm, the wire placement is generally more consistent (assuming the machine is maintained and the servo motors or pneumatic actuation are providing repeatable wire position). Monitoring the terminal de-reeling and inspecting the crimped wires is still an operator based process.

Operator training and process monitoring can improve process variation.

 Process Improvement Tools

Crimp Height Micrometers

CHT Mic

A specially tooled micrometer with a pointed spindle and flat anvil. The spindle is positioned on the underside of the terminal to avoid false readings from the anvil crimp tool impression on the terminal. A pre-process and in-process inspection tool. A model with output capability can provide data for capability studies and for data archive.

Pull Tester

OLYMPUS DIGITAL CAMERA

A destructive test. Checking the secure-ness of the crimp. It should be noted that most pull test specifications are for the wire crimp only. The insulation crimp must be peeled back prior to performing the pull test. A pull tester is normally a pre-process inspection tool. Output as described above is a good feature.

Crimp Cross Section

image003

Cutting the crimp in half and viewing inside is becoming a required quality validation process in a growing number of industries. A cross section analysis provides valuable information on strand distribution within the crimp and overall compression analysis. Designed as a pre-production analysis tool as well as validating the crimp after changes to the process (any of the five elements).

Crimp Force Monitor

MX

Statistically speaking, 100% visual inspection is only 80% effective, leaving a high risk of 20% of production not fully inspected. A crimp monitor measures each termination in real time and compares the results with initial samples of terminations inspected and validated for production. All five elements described above are monitored as a whole. Crimp monitors take the decision making process away from the operator and provide a base line for the crimp process as a whole. As a process improvement tool, single improvements to the process will show as an improvement in the variation of the crimp curve. Providing an opportunity to reduce the process tolerances to detect smaller variations. The crimp monitor is a standard in process monitoring tool for most industries. Even without a customer mandate, a crimp monitor is a good tool for in process inspection and process improvement.

Press Analyzer

PAL_600 rev

Calibrating a press to the required shut height only assures capability to the single calibration cycle. Ensuring the press meets a statistically controlled capability is an extension of the calibration process and assures the press can provide the repeatability required. Typically companies calibrate and run capability studies once per year, semi annually or quarterly depending on the volume being processed. Analyzing a press’ shut height and reference forces also allows maintenance personnel to prioritize maintenance schedules.

Summary

Improving the overall quality of a terminal crimp requires an evaluation of all five process inputs. Assuming what previously was acceptable is still acceptable or what is seen on the surface is acceptable under the surface is not a good quality strategy. Implications can be as basic as a circuit failure or as broad as product failure causing damage to property or injuries to the end user. There are real life examples of these conditions occurring which have caused damage to people, property and your company’s reputation. The risks in today’s business conditions are real but can be greatly reduced by adopting and maintaining a comprehensive quality validation, monitoring and improvement strategy.

More information on quality validation and monitoring of the terminal crimp can be found in our three part special: Part One, Part Two and Part Three.

Connect Your Way to WPS to hear how we can support your wire processing requirements.

Crimp Quality Process Validation and Monitoring Part Three

This is the final installment of Crimp Quality Process Validation and Monitoring.  In part one, we discussed pre-process validation. In part two we outlined real time monitoring process during production.  In this segment, we will discuss the calibration and machine capability of crimping presses as an integral part of an overall quality strategy.

Process Capability
Process Capability is the total variation in a production process and the ability for that process to be reproduce-able over time and within stated production specifications.  Measurements during the production process are taken then grouped together to form a histogram (bell curve). The distribution of measurement results provide an indication of present conformance of the item being produced.  Process Capability is a valuable tool for making changes to improve the production process. The capability of a production process is based on multiple factors which are common among almost all production processes The major factors are People, Machine, Methods and Materials. Each factor has its own process variation and contributes to the overall process capability.

In crimping a wire to a terminal, these factors above come into play and can be controlled at the plant level in different degrees.  For example:

Considering “People” as a factor, the manual locating of a terminal in a bench top crimp press is one level of variation. Training operators improves the process and is eliminated when an automatic processing machine is deployed.  Methods can range widely but could include maintenance schedules, operator and set up personnel training, set up and operating procedures.  Effects the Machine has on the process can include the machine age (wear and tear), maintenance and overall accuracy and repeatability of the machine itself.  Machines can include the crimp press, terminal applicator and in the case of an automated machine the robotic assembly to deliver a stripped wire to the crimp press.  The factor which the producer has less control is materials which include wire, terminals and weather seals.  In the case of materials, specifications are generally established by the material manufacturer within their own production process.

Crimp Press Capability

The machine component which can cause excessive variation in the process and which is the last area companies look to for process improvement is the crimp press itself.  Even with stable materials, methods, people and crimp applicators additional process variation can occur with the crimp press.  Presses have a long production life cycle and in that time bearing, crankshafts and ram assemblies can get worn. Which will show up as piece by piece variation.

The illustration at the left shows a chart of a crimp press which was calibrated and the press was cycled to determine peak crimp force per piece.  The top chart shows the shut height measurement and the bottom chart shows reference force.  Excessive variation can be found in the force chart on a piece by piece basis.  The shut height measurement was in control where the force was not in control.

The illustration at left was the same press after maintenance was performed to tighten up the press ram assembly.  The force measurements were brought into statistical control.  The shut height measurement also improved statistically. The result of this improvement will be a process that is in better statistical control and a product which will perform consistently better piece by piece.

The tool used is the C&S PAL3001 which can calibrate a press to the industry standard shut height and take force measurement readings to determine machine capability.

 

 

 

Wire Process Specialties can supply your crimp validation equipment and in-process measurement and data collection for ongoing process improvement.  Connect You Way to WPS find out more.