3 Reasons Why Coil Cords are Important in a Wireless World

Coil cords are everywhere, from the back of a semi truck, to a camera’s flash strobe to the arcade games where you manipulate a claw to pick up a toy.  Coil cords are used in a wide variety of industries too.  Coiled cables are used by the medical industry, security industry and industrial control industry to name but a few.  And in this age of everything wireless a good question is why would anyone use a coiled cord?  So no matter what you call it, a coil cord, curly cord or coiled cable this article will give some reasons why a coil cord is still the right solution for many applications.

1)      There are three main reasons to use a custom coil cord instead of wired solution.  The first is power.  While wireless solutions exist for many application when electrical power needs to be supplied it almost always is done with wire or cable.  When something is wireless it means the product uses radio waves of some sort.  Radios that we listen to are one example of just such a product.  We could connect all radios with coil cords and send the signal along the cord, but that isn’t practical for long lengths of distances, so radio waves are used to send the signal.  When radios waves are sent they move in all directions and don’t really care what they hit, and don’t react with anything but antennas “tuned” to their frequency.

Power is different.  If power was transmitted like radios wave it would interact with anything metallic in its path.  And if the metallic object was connected to something the power would transfer from the metal to the object.  This would act as conductors, and could be very bad as in the extreme case of lightning, which is a very powerful wave of energy.  So cables, and coil cords, are used as a part to transfer power for obvious safety reasons.

2)      The second reason coiled cables are used instead of wireless is to avoid electronic noise.  We live in a world filled with radio waves all around us.  Often custom coil cords are used instead of radio waves because the items needing the signal would be damaged or impaired by other signals.  A classic representation of this is again a radio, only the old AM kind.  We have heard static and other stations fade in and out on radios.  The static we hear is noise.  If a coiled cord was used instead of radio waves, and the radio was shielded from outside waves, we wouldn’t hear static.  However connecting all radios with coil cords is impractical, but in an operating room it isn’t.  This is why cables and coil cords are often used in hospitals.

3)      The third reason to use a coil cord instead of wireless signal is security.  In the early days of cell phones, it wasn’t unusual to be talking with someone one moment and the next be speaking with someone else.  This was because the cellular phone systems and their suppliers at that time were not as advanced as now.  For most people this is not an issue, but if you are in the military it can be a matter of life or death.  Having a coiled cable transmit signal or power ensures there will be no interruptions.  Imagine a surgeon in the operation room losing power at a critical point in surgery.  This is why where failure is not an option coiled cords are often used.

Wireless products are great, and they have made our lives much more mobile and easy.  However as the above points show custom coil cords and cables are still very necessary.  If you need power, a clean signal or security of transmission a coiled cable is a great solution.  Meridian Cable manufactures and designs coil cords for any coiled cable need you have.

We have all seen them, those curly wires that are used to connect things and stretch like a spring.  Coil cords are found in garage doors, your cell phone car charger, defibrillator paddles and simple key chains.  Coil cords are a great way to attach two items where one or both need to move.  Whatever the application knowing how and what mechanical tests are needed to verify a coil cord design is critical in achieving proper performance. 

All coil cords have the same general shape, a straight section, followed by a coiled or curly section, followed by yet another straight section.  The extension capability of a coil cord comes from the coiled or curly section.  When the cable is pulled the coiled section acts like a spring and stretches.  It is this mechanical stretching that makes this type of cable assembly critical in certain applications.

Since a coil cord is a dynamic assembly care must be taken to ensure the design will last the expected life of the product.  Advanced life testing is one way to verify the design meets the required specifications and can perform as expected.  The testing discussed in the article are Cycles to Failure, Retraction Compliance and Cable Flexing to Failure.

Coiled cables are springs made from raw cable that is typical composed of copper and plastic.  As we have all seen, if copper or plastic is repeatedly flexed it can fatigue and eventually fail.  When a coiled cable is extended and then retracted flexing is occurring.  This flexing, over time, will fatigue the materials.  The best way to determine if the design can withstand this process is to perform a Cycles to Failure test. 

In a Cycles to Failure test a coiled cord or cords is attached to a test machine that can be programmed to extend and retract the cable.  The test machine’s extended length, cycle speed, extension dwell and retraction dwell can all be programmed.  For example the machine could be set to 110% of designed extended length, a cycle speed of 30 per minute, an extension dwell of 10 seconds and a retraction dwell of 20 seconds.  The machine would then cycle the cable or cables until an open circuit occurs indicating failure.  All the parameters can be changed to align properly with the intended application.

In a Retraction Compliance test the cords are attached to the cycling machine and cycled.  However before cycling the coil cable’s initial retracted length is measured.  After cycling the cable is allowed to rest for a period of time and then the cycled retracted length is again measured.  Retraction Compliance is defined as a percentage of cycled retracted length to initial retracted length.  These percentages can range from 50% for a very poor or heavily cycled coiled cable to 95% plus for a well designed assembly.

The Cable Flexing to Failure test is used to make sure the raw cable used itself can withstand fatiguing.  The coil cord is made and sections of the cable, both the coiled section and straight section, are attached to programmable cable flexing machine.  The machine’s flex radius, cycle speed and rotation angle can all be customized to ensure the cable meets the desired requirements.  For example the flex radius could be ½”, the cycle speed could be 60 per minute and the rotation angle could be 180 degrees. The machine would then cycle the cable until an open circuit occurs indicating failure.  All the parameters can be changed to align properly with the intended application.

Designing a coiled cable properly is critical.  Over engineered and the cost is too high; under engineered and the performance is inadequate.  However the only way to ensure the design is correct is through testing.  There are two types of testing.  Lab based, programmable testing which Meridian Cable performs, or field testing which everyone who buys a coil cord eventually does.  In many cases the lab based testing before field launch will help ensure a proper cable is designed, manufactured and delivered.

Should you need a standard coil cord or a custom design coiled cable Meridian Cable can help.  Meridian Cable has over 30 years of experience designing and manufacturing coil cords, coiled cables and cable assemblies. Designed – Built – Delivered, Meridian Cable is ready to help create a solution for you.

Many people are gullible enough to believe that EVERYTHING imported is of poor quality.  This simple defies logic and anyone who makes a blanket statement as such surely doesn’t know the world we live in today.  Meridian Cable makes coil cords in China, designs them in America and is creating jobs in BOTH countries.  This cannot be said by some of our competitors.

First let’s address the quality issue.  If you have bought a cell phone, laptop computer, television or many other electronic devices odds are it was imported.  The same is true for many, many other items.  Kitchen appliances, furniture, medical devices, industrial controls and caskets are just a few of the items imported into America from overseas.  If the argument is true that everything imported is of poor quality how is it that there are excellently made examples of every item listed here?  The same is true of coil cords and cable assemblies.  The truth is you can find poor quality manufacturing ANYWHERE, and that includes America.  The important thing is to find a reputable company with a long history of quality performance.

Second let’s discuss why anyone would make such a blanket statement.  There are great manufacturing companies all over the world, and there are very poor manufacturing companies all over the world.  In this day and age surely everyone knows that excellent performance is not limited to any nation.  Anyone who thinks one country has all the advantages is limiting their option.  Granted there are reasons to buy from a given country and those do count.  However if quality is the only criteria then there are many countries that qualify.  The same is true of coil cords and cable assemblies.  The truth is you can find companies at each end of the quality spectrum in most countries.  A smart assessment would include ALL companies that can perform and not limit the options based on geography.

Third it is helpful to remember how small the world is today.  Sure the earth has not changed size in our lifetime, or for a few billion years for that matter, but from a business standpoint the world has never been smaller.  It took Christopher Columbus 5 weeks to cross the Atlantic in 1492, the first steamship took 18 days, Lindbergh 33.5 hours and today a modern jet makes the journey in 7 to 8 hours.  Technology has continuously made the world smaller with each passing generation.  Anyone who denies this fact is either purposely not telling the truth or is clinging to a lost world.

Last we all need to remember our business history.  There are countless examples of countries and companies who close themselves off to the options the world can afford.  China for example in 1100’s had paper, gunpowder and the compass CENTURIES before Europe.  And in the 1400s, 80 years before Columbus’ voyage they had 400 foot long, ocean going boats while Columbus’ boats were about 70 feet long.  China closed their borders, burned their boats, and was not a serious economic power for the next 500 years.

The point is obvious; any company that wants to grow and be competitive has to take advantage of every opportunity and resource available.  Anyone who says ALL the advantages are in ONE country is either not being honest, or is myopic and denying reality.  In today’s business environment, with the advancing in communication and logistics, any company can buy from any other company.  All it takes is find thing right partner.  When it comes to coil cords and cable assemblies Meridian Cable, being a global company, can be the best partner an OEM can find.  And we have added many jobs in AMERICA over the last few years, so if you are worried about American job creation Meridian Cable is doing that too!

Whether you call it a coil cord, coiled cable or retractile cord we have all seen the spiral cords used in many applications.  From garage doors, to cell phone car chargers, to medical equipment these cables are critical in achieving many design goals.  Whatever the design goal the primary reason for using this type of solution is to put a lot of cable or wire into confined space and have it available to extend when necessary.  Coil cords are a great way to accomplish this goal.

 

All coil cords have the same general shape, a straight section, followed by a coiled or curly section, followed by yet another straight section.  The extension capability of a coil cord comes from the coiled or curly section.  When the cable is pulled the coiled section acts like a spring and stretches.

 

For many applications the time required for a coiled cable to retract from its full working length is critical.  A number of factors influence the retraction speed of a coil cord but one important consideration is the raw cable’s geometry.  This geometry is typical round, but in special it can be rectangular or even ovate.  The advantages of each shape and the corresponding “bean effect” are explored below.

 

Every coil cord requires forces to extend it.  That force comes from the unwinding of the coils themselves but also from the bending of the raw cable along its length.  If viewed from the individual coil perspective what is happening can best be described as beam being bent.  In a round geometry the force required in any given direction is equal.  An easy way to visualize this is with a metal coat hanger.  If a straight section is held tight at one end and the other end pushed from the side, from the side, the force required to bend it in any direction would be very similar.  While other factors such as fabrication stresses, molecular orientation or grain do have an effect to some degree it is quite minimal in this application.  This design creates a coil cord with a typical retraction speed.

 

In order to achieve a faster retraction speed a coiled cable made from a rectangular shape cable can be used.  The rectangular shape adds force that can be best visualized using a ruler or a regular 2 X 4 board.  When these are laid flat with something supporting just the ends the middle is free to bend, and depending on the length it can bend quite easily.  However if the direction is changed and these are placed on edge they will not bend much at all.  When a coiled cord is made using a cable with a rectangular cross section this resistance to bending, or “beam effect”, augments the spring effect of the coils and creates a coil cord with a higher retraction speed.

 

Sometimes a round geometry is too slow and a rectangular geometry too fast.  In these instances a cable with an oval geometry can be used.  Since this cable is not round it has a higher beam effect, however since the cable is not fully rectangular the beam effect is less.  As one can imagine there are many variations between round and rectangular.  All the options lead to many design opportunities when designing a custom coil cord.

 

Should you need a standard coil cord or a custom design coiled cable Meridian Cable can help.  Meridian Cable has over 30 years of experience designing and manufacturing coil cords, coiled cables and cable assemblies. Designed – Built – Delivered, Meridian Cable is ready to help create a solution for you.

At Meridian Cable our tag line is “Off Shore ­ In Spec ­ On Time™” and we specialize in custom coil cords and custom cable assemblies.  Since most products we build are designed, tooled and built exclusively for our customer’s many folks believe our lead times would be quite long.  This is far from the truth.

Recently Meridian Cable was fortunate enough to work with a new customer who was in a bit of a pinch.  This company was in Hawaii filming a sequel to a major motion picture, and they needed some custom coil cords fast.

The common perception is lead times from China, where our wholly owned factory is located, are months long.  We shipped this order in less than one month from first contact.

Our new customer found us through an internet search, sent us an email and we had a quote to them in 2 days.  Again this is a custom coil cord and not something we keep in stock.  If this had been one of our stock coil cords we could have shipped the same day.  We designed, costed and quoted this product in 2 days, and then proceeded to deliver them to the customer in less than 4 weeks.

To put some perspective on how quick this is, an explanation of how a coil cord is made will help.  The first step is to build the inner conductors.  This starts by taking individual copper strands and combining them to make the gauge wire needed.  Step two is to cover this wire with an insulation material such as PE, HDPE, PP or PVC.  In step three we combined three 26 gauge wires and a 24 gauge drain wire together in a bundle.  Step four was braiding whereby the wire bundle is cover in a shield made up of 64 inter woven strands.  In step five we did the final extrusion with PU, polyurethane.  All these steps just made the raw cable; we still had to make the coil cord.

Coiling cable involves winding the raw cable around a metal rod.  The size of the rod and length of the winding will determine the size of the final product.  After winding the rods are put through a heat treating and cooling process to make sure the raw cable holds the curly cord shape that gives the product its retractablity.

Then all we had to do was ship the product, from China to Hawaii, where our customer was on location shooting their film.

All this was done in less than 4 weeks.  This is what “Off Shore ­ In Spec ­ On Time™” means at Meridian Cable.  Call or email us and see how we can help solve your custom coil cord or cable assembly needs.

Bud Kinzalow ­ Meridian Cable

Meridian Cable recently helped a customer turn a mess of 3 coil cords into 1 neat solution.

The existing design used 3 coil cords, 4 DB9 connectors, one Molex connector and one DC power plug.  All 3 coil cords were in a tube and would get tangled up.

Meridian Cable’s engineers designed one coil cord with 2, 24 gauge conductors and 24, 28 gauge conductors eliminating the needs for 3 separate coil cords.  This design also included over molding the DB9, Molex and DC power connectors.

Call us or fill out our contact form if you need coil cords designed or quoted.

Bud Kinzalow-Meridian Cable