Reverse Engineering: Why you need it and when.

Do you need a wire or cable and have no idea what it is? You are not alone, it happens more times than not especially for equipment repairs, obsolete parts, and failure analysis. When do you need to have a cable reversed engineered? You may like a particular cable's performance or you have a piece of cable that you or your customer may want more of but don't know what it is or who manufactured it. Then reverse engineering is the answer. Who performs this service? Most custom wire and cable manufacturers can assist you.

Reverse engineering wire or cable is commonly performed to determine:

• Conductor stranding and material.
• Cable construction
• Insulation and jacket materials

Custom wire and cable manufacturers routinely reverse engineer wire and cable to identify the materials used and the cable construction. It is best to provide a sample between 1 to 2 feet if possible and keep in mind it will be dissected in the process.

Outer jacket
Reverse engineering wire and cable begins with measuring the outside diameter (OD) of the wire or cable. The longer the piece the better it is to obtain the nominal OD. The outer jacket is carefully removed to expose the core. Normally, cross sections are taken of the outer jacket to measure wall thickness. Jacket material is tested to identify the type of material used.

Braid, shield or tape
If there is a braid or shield the construction will be examined. The pitch, number of ends, material and coverage can be determined at this point. If there is a tape wrap present, the overlap, type of material and size will be examined.

Core construction
The next step is to examine the cabling construction. Once the shield and/or tape is removed the following can be determined: Cable lay or twists per inch, filler material used, the use of strength members, number of conductors and conductor color code.

Conductors
The conductor material, plating used (if any), gauge and conductor strand count and construction are checked. A cross section of the conductor will identify the wall thickness of the insulation and OD. At this point the insulation material will be identified.

Insulation and jacket materials
There are several ways to identify the materials used for insulation and jackets. The obvious is the look and feel of the insulation or cable jacket. Computer analysis and burn testing are also used. Plastics and rubber each have distinct characteristics when placed on a flame. Experienced engineers can determine the type of insulation material by whether it burns, melts, or self extinguishes. The odors produced when burned also are distinct to each type of material. Burn testing should only be done by experienced individuals in a controlled environment, gases can be toxic as well as the risk of fire is present.

Failure analysis
Failure analysis is another reason for reverse engineering wire and cable. When a cable fails, determining the cause can many times be done with reverse engineering to pinpoint the problem. Common problems with handheld devices with poor strain relief is damage to conductors or conductor stranding due to excessive bending. Shielding materials can over time damage conductor insulation. Dissecting the cable at the problem area can expose the problem. Custom wire and cable manufacturers can make material suggestions such as the use of higher conductor stranding or alloys, insulation materials or cable construction design alterations based on the findings of reverse engineering.

Flexible Wires To Flex or to Hi-Flex?

Flexible wire and cable can have more than one meaning depending on who you ask. To some, very flexible wire can mean able to withstand repetitive flexing while to others it describes the limpness of the wire or cable. When describing a "super flexible wire" to your wire and cable manufacturer be sure to be clear on which you need either hi-flex or limpness. Is there a difference? There is a difference between the two types of wire and cable which begins with the conductor stranding and material.

High flex cycles and repetitive flex wire and cables are specialized for these types of applications. Whether you are working with a custom wire and cable manufacturer or buying commodity robotic cables, special attention should be taken with regards to the conductor stranding and material. Specifying a high strand count alloy conductor in your wire and cable design is key to the longevity of the cable. Lower strand count conductors such as a typical 19 strand will not last long in a hi-flex environment, as the individual strands break due to the stress and fatigue, the weaker and less conductive the conductor will become until it inevitably fails. High strand conductors can be constructed in a way that the stress of flexing is absorbed by the large number of fine strands and having a few strands break will not affect the conductivity as would in a 7 or 19 strand construction.
The use of high strength alloys is recommended for hi flex life. They offer high breaking strength and greater flex life with only a small increase in DC resistance. Cadmium-chromium copper, cadmium copper, chromium copper, and zirconium copper are most frequently used. View our conductor stranding page for types of conductor configurations available and our wire gauge table for stranding options.

A wire and cable company will usually offer hi-flex and repetitive flexing applications can be found in:

• Robotic and automation
• Medical and surgical hand pieces
• Sensors and instrumentation
• Aerospace

Flexible wire and cable in terms of limpness also requires high strand conductors but may not require the use of alloy materials depending on the application. Descriptions of this type of wire include:

• Ultra flexible wire
• Noodle wire, noodle like
• Hi flex
• Limp wire

The other key to flexible wire is the insulation or jacket material choice. There are many flexible materials depending on your requirements. The most flexible insulation material is silicone rubber, but depending on your application it may not be right for you. When discussing your flexible wire requirements with a wire and cable company be as descriptive as possible and discuss the application in order to narrow down your material choices. Flexible wires are available in most gauges. The wire pictured here is a 1050 strand 6 AWG and is extremely flexible and quite limp. Custom wire and cable manufacturers usually stock high strand conductors for flexible and hi-flex wire applications.

Custom Cable & Wire Design- 5 Myths of Custom Cable

There are many misconceptions when it comes to the subject of custom made cables. Many designers shy away from using custom cables due to not knowing what is involved or they have dealt with manufacturers who do not specialize in custom cable designs. Here are five myths that we can clear up.

1. Really expensive - People that are new to designing products often think you need thousands of dollars to have a custom cable made. The truth is for as little as $500 (sometimes less) you can have custom wire or cable made to your specifications. When comparing custom wire and cable to the "off the shelf" custom is obviously more expensive, but we are not comparing apples to apples here. Custom cable is designed to your specific product or application requirements which may require special materials or construction. In the early stages of product development where small prototype quantities are needed, the cost of the cable can be higher than production quantities.

2. Huge minimums - Using a custom wire and cable manufacturer is important. Custom cable manufacturers are set up to run many types of materials and constructions and usually have to set up the machinery for each job. Minimums are small or non existent. Commodity/ off the shelf manufacturers normally are running the same materials and construction over and over, so for this type of manufacturer to stop production to make an unusual cable is costly. If you approach a commodity manufacture, it is not uncommon to be quoted a 10k-15k minimum. Unless you are using an unusual or uncommon material that itself has a minimum buy, you can order small quantities from the custom cable manufacturers.

3. Expensive tooling charges - Custom cables do not normally do not require special tooling. Tooling charges or N.R.E. can be expected for custom printing, unusual shapes and flat ribbon cables which require special dies to maintain wire pitch and extruded shape.

4. Long lead times - Custom cable lead times can vary depending on material availability and construction. On the average hook up wire can have a 2-4 week turn around and cables can run 3-6 weeks. Commodity cable manufacturer lead times for custom cable can run 8-14 weeks or longer.

5. "I need to know all about wire & cable" - Design engineers sometimes shy away from custom cable designs because wire and cable is not their forte. Custom cable manufacturers have engineers and custom wire and cable designers on hand to assist their customers with choosing the right materials and construction. It's like having a wire and cable expert on your team. Cable designs are usually at no additional cost.

Of course there are exceptions to the statements listed above. Lead times and minimums can be affected by material choices and complicated cable designs. When considering custom wire and cable designs for your product, be sure to contact a custom cable manufacturer. Working with a company which manufactures custom cable products enables you to buy smaller quantities, faster turnaround, and you buy a cable specifically made for your application.

Medical cables and sterilization

Medical cables are manufactured using a variety of materials. Reusable medical cables often times are subjected to sterilization processes and are built to endure extended cycles of sterilization. Understanding how a wire or cable will be sterilized is crucial to determine what materials to specify when designing a medical device. Insulation and jacket materials vary when it comes to resistance to chemicals, heat and other sterilization techniques.

Common types of sterilization include:

• Heat/steam - Autoclave
• Chemical
• Irradiation - E-Beam & Gamma Ray

Autoclave (heat/steam) resistant materials for reusable medical cables include FEP®, TPE, silicone or with TPR or silicone rubber jackets. Radiation resistant medical cables can be made with silicone and Teflon® (if water is not present). TPE and PVC can be made for Gamma sterilization with limited sterilization cycles. PVC is not commonly used with chemical sterilization, alcohol based liquids can break down the plasticizers (an additive for PVC) and can make the PVC brittle and damage the insulation or jacket. PVC is more commonly used with disposable applications.

It is always best to discuss with your custom cable manufacturer what types of sterilization and how many sterilization cycles the cable will be subjected to. Cable manufacturers experienced with medical cables and their applications can help narrow down your choices based on sterilization techniques, bio-compatibility and other requirements.

Silicone Insulated Wire- Medical Grade Silicone Applications

Silicone insulated wire and cable is an excellent choice for medical cable applications. Besides being extremely flexible, silicone rubber can withstand autoclave and other forms of sterilization. Properties that make silicone suitable for medical applications include: Low thermal conductivity, low chemical reactivity, low toxicity and thermal stability (consistency of properties over a wide temperature range of 100°C to 250°C). Abrasion resistance is a concern when considering silicone insulation or jacket. Formulas for higher tear strength are available to increase resistance to abrasion.

Applications suitable for silicone cables include:

• Arthroscopic
• Surgical Robotics
• Electrosurgical
• Implantable
• Ophthalmic
• Foot Switch
• Patient Monitoring

What makes a material medical grade? Materials are tested for bio-compatibility and are categorized to be used for medical applications. Medical grade materials are generally grouped into three categories: non implantable, short term implantable and long-term implantable. Materials approved as USP Class V and VI can be considered medical grade, most medical grade silicone is at least Class VI certified.

Uses for medical grade silicone cables include:

• Tubing/Lumen
• Drains
• Feeding tubes
• Catheters
• Implants for long and short term use
• Sensors

Co-extruded and multi-layer silicone cables can be used for high voltage applications such as X-Ray and MRI equipment which require electrical noise suppression and limited power loss . Co-extrusion involves extruding a semi-conductive silicone layer around the conductor to remove air thus reducing corona. Extruding both semi-conductive layer and jacket simultaneously insures no air or particles are caught between the layers. Benefits for co-extruded silicone include corona, moisture & ozone resistance, lightweight and flexible cable design and radiation resistance to name a few.

When working with your custom cable manufacturer, it is crucial to provided them as much information as possible about the application, the environment, sterilization and bio-compatibility requirements. The more information you can provide to your silicone cable manufacturer will help in determining if silicone is right for your application and to offer you material choices that will enhance your product's performance.