We have our own in-house cutting shop. This means we can supply specific lengths on almost all of the tubings and sleevings we sell. We can cut to just about any length needed and our equipment allows for very tight tolerances.
As you’d hope, we’re more advanced than the ruler and scissors method we mentioned below. Here’s a quick list of methods available from our cutting shop:
Hot knife cutters – for cutting braid and prevent fraying
Standard vertical blade cutters – for accurate and clean heat shrink sleeve cutting
Tolerance cutters – for tight cut length tolerances, as well as controlled angle of the cut
High volume commercial – used for high quantity runs
AlWe provide, as standard, bags containing tubing cut into:
If you need something different to the standard offerings above, e.g. bulk enquiries or small batch runs, then do let us know. We’re more than happy to help and numbers can be customised to suit.
Doing it yourself
A ruler and a pair of scissors (or a sharp knife) will mostly do the job especially if exact lengths aren’t required and you are cutting just a small amount yourself.
If the heat shrink tubing you have won’t fit over obstructions (like a connector), then what you have won’t do the job. As they say in Hollywood, “we’re gonna need a bigger heat shrink” (or something like that). This might be with a bigger shrink ratio too as it still has to drop down to the size you need.
Why can’t you cut heat shrink length-ways?
Heat shrink is manufactured to the shrunk size, stretched and then sold. (Wikipedia explains the manufacturing process in a bit more detail). Cutting it cross-ways is fine. But, when you cut tubing length-ways it loses integrity which is why we don’t recommend it. There are various forums where people have tried different suggestions – spiral cuts, glueing etc but they all have the same problem, lack of integrity – eg no longer waterproof and it no longer protects against the environment. (And so fiddly).
Where is the best place to buy heat shrink tubing?
We explain what to look for when you buy heat shrink tubing, so that you get the correct product needed for a successful project …
You’re ready to buy it but need to know where is the best place to buy it from? Actually, rather than asking “Where can I buy heat shrink”, a better question might be…
“Which company can help me make this project a success? After I’ve applied the product and shrunk it with a heat gun, I don’t want the tube to still be sliding up and down like kitchen roll liner on a washing line!”
That’s just one of the possible pitfalls in choosing the wrong product. Here’s a list of six and a half things to help you decide where to buy your tubing.
1. Location, Location, Location
What should you watch out for when choosing a supplier? Their location details are a useful starting point – check the supplier’s website.
They don’t need to be just up the road, but do check for a physical address. If there are no contact methods other than the contact form, then alarm bells should start ringing.
Are they in the UK for straightforward delivery rather than you having to buy from overseas (and possibly having to deal with import issues through Customs).
Is it a bare bones site with just products, a shopping cart and no supporting information? In other words are they just a warehouse (or drop shipper) after the next quick sale.
Is there a contact number so you can call for support? Talking of support …
2. Technical knowledge
Does your prospective supplier have the technical knowhow to support your purchase?
Getting the right product is more than just a quick transaction to buy the right diameter and shrink ratio. It needs to to work long after it’s been installed and that means planning for factors that could degrade the sleeving.
There’s more to know than just the product though. Has your potential supplier experience of their products in multiple markets? It’s great if they’re specialists in the communications niche but if you need the product to survive in a harsh marine environment then you’ll need support and expert knowledge that will help you make the right choice.
3. Colours (and other options)
If the technical knowledge is available but the only colour is black (and you need red) then obviously that’s an issue. A wide range of colours, options and specifications will make sure that, for example, when you need a low outgassing heat shrink for a satellite comms module operating in space it’s there for you without having to start your search again for yet another supplier for this new requirement.
4. Technical Services – cut to size
Can your prospective supplier support you after you’ve selected the product? Do you need it cut to a specific size or in a special way? For example:
High tolerance cut
After it’s been cut, would it help to have it put into a kit for your team? Different sizes, colours and lengths all ready and prepared (as per your component list or bill of materials) so all your assembly team need to do is open the lid of the kit and start work.
Let’s not stop there though…
5. Technical Services – printed and posted
Would it help to have your heat shrink printed with your logo, serial numbers or other useful text/graphics? If this is important then wouldn’t it be more efficient to have it done by your supplier, rather than sending the products on to a print shop.
Talking of sending things…
How would you like your product packaged? In a bespoke wrapping with your branding (or your customers’)? Palletised?
Once it is on its way, there’s the problem of where to store it. Can your supplier keep it for you until you are ready (just-in-time)? Would it help to plan the inventory and delivery scheduling?
6. Mind the quality
So far everything is going to plan – you’ve found a supplier who can provide the right product, backed up with the experienced technical knowhow and cut and printed just how you need it … hopefully.
If when the product finally arrives, it doesn’t match expectations then all that effort has been for nothing. It’s worse in fact because you’ll need to undo what’s been done, find another supplier and go through the whole process again. How do you avoid this?
Look for quality assurance. How does your potential supplier prevent mistakes and avoid problems? Are they certified to ISO9001: 2008, the international standard for a quality management system (QMS) which means they are focussed on:
6.5 Are they humans?
A strange question, but fair. when you buy heat shrink tubing, and you are digging around a website, can you see anything about the team that you’ll be working with? Some organisations rather worryingly portray themselves as a faceless business with minimal contact information – just anonymous robots to process your order. Look for staff photos, bios, multiple ways to get in touch and a knowledgebase of useful information.
So that’s it. Six (and a half) questions to ponder while you are thinking of where to buy your heat shrink.
Of course, (as you’d expect) we do meet all the points in this list and we’d love for you to come to us for your sleeving and tubing needs.
The most important aspect of choosing the right heat shrink tubing product for your needs is to understand and define all that is necessary for your application. The only way to ensure that you’re getting the most appropriate and cost-effective product is to fully understand your application and the requirements that you need to meet.
Regardless of whether you’re using heat shrink tubing in an electrical application, as a strain relief, as a protective covering, or for any other reason, determining the correct size is the most important factor.
A great start point is to measure the 2 most important dimensions:
The largest diameter that the expanded sleeve needs to slide over
The smallest diameter that the tubing needs to completely cover to (after shrinking).
These two dimensions will be used later in Step 2 to help you determine the required size and shrink ratio for your tubing.
Another important dimension to consider is the wall thickness. A certain minimum wall thickness might be required due to the electrical requirements of your application. Or, if the tubing is going to be subjected to excessive abrasion or wear, you may wish to have a heavier wall thickness than the standard size offers. In addition to defining your required minimum wall thickness, it is also necessary to determine the diameter at which this wall thickness will be required. This information is critical in choosing the required tubing size in Step 2.
Electrical Property Requirements
If your heat shrink tubing is going to provide electrical insulation or bundle electrical wires, it is likely that it needs to meet certain regulatory guidelines. In order to choose the correct product for your application, you’ll need to know if any specifications need to be met. In the heat shrink world, the most common ones are listed below
UL (Underwriters Laboratories)
CSA (Canadian Standards Association)
ASTM (American Society for Testing and Materials)
AMS (Aerospace Material Specification)
EU (European Union)
RoHS (Restriction of Hazardous Substances Directive)
VDE (Verband der Elektrotechnik)
There are literally hundreds of industry or application based specs that you may need to consider, automotive or military specifications are very common and can differ greatly from one manufacturer to another, but regardless of the origin, these specifications all tend to be in place to cover common electrical requirements such as dielectric strength and flame resistance.
Other possible electrical requirements could be that the tubing must be free of halogens or that it must be made out of a specific material. Make sure you understand all of the electrical requirements before you choose your heat shrink product.
Another critical step in defining the requirements of your heat shrink tubing application is to understand the environment in which the tubing will operate. For example:
Will the tubing be subjected to excessive abrasion or flexing?
Will the tubing come into contact with any oils, greases, fuels, chemicals, or other fluids?
Will be used indoors or outdoors?
If it is going to be used outdoors it could be subjected to excessive UV exposure.
If it is going to be lying on or buried below the ground, it may need to have superior resistance to fungus growth.
Does the application require an enhanced environmental seal (as obtained with adhesive-lined heat shrink tubing)?
Will the tubing need to protect any sensitive portion of the object the tubing is covering?
All of these factors and more will need to be considered prior to selecting your heat shrink product.
Step 2: Determine the Required Tubing Size
The next step is to determine the most appropriate tubing size for your application. Using the measurements you obtained in Step 1, you’ll need to define the following tubing dimensions that best suit your needs:
Minimum expanded ID
Maximum recovered ID
Minimum recovered wall thickness.
This section will explain each of these tubing dimensions and how they relate to your application measurements found in Step 1.
Expanded and Recovered Inside Diameters
Heat shrink tubing is traditionally specified by the minimum original inside (“expanded”) diameter and the nominal shrink ratio. However, a good heat shrink product datasheet will not only list the minimum expanded ID and nominal shrink ratio of the tubing, but also its maximum recovered ID.
First, check that the minimum expanded ID of the tubing is greater than the largest diameter that the sleeve needs to slide over (using the measurement you made in Step 1). Then, check that the maximum recovered ID of the tubing is less than the smallest diameter that needs to be completely covered (also measured in Step 1).
The diagram below illustrates these tubing dimensions:
If the product datasheet does not have maximum recovered ID listed, you can estimate it using the minimum expanded ID and the shrink ratio.
If a heat shrink product has a 2:1 shrink ratio and the minimum expanded ID is 6.4mm, then the maximum recovered ID should be 3.2mm
6.4mm ÷ 2 = 3.2mm.
If a heat shrink product has a 3:1 shrink ratio and the minimum expanded ID is 39.0mm, then the maximum recovered ID should be 13.0mm
39.0mm ÷ 3 = 13.0mm.
Now that you have determined the required expanded and recovered ID’s (and also the shrink ratio), you may need to consider the wall thickness required for your application.
The wall thickness of a heat shrink product is traditionally specified as the minimum thickness at the fully recovered stage. If the diameter of what you are covering is greater than the maximum fully recovered diameter of the tubing, the final wall thickness will be less than what is specified on the datasheet. This is illustrated below:
The dimension trec is the wall thickness of the tubing when allowed to shrink fully without restraint. However, since your object is restraining the tubing from shrinking fully, you’ll need to determine the required tact before you can specify the tubing. The approximate relationship between the two thickness dimensions is as follows:
t rec= (d obj x t act) ÷ d rec
t act = (d rec x t rec) ÷ d obj
t act = actual wall thickness after shrinking onto the underlying object
d obj= diameter of the underlying object
t rec= specified recovered wall thickness of tubing
d rec= specified recovered diameter of the tubing
Length & Longitudinal Shrinkage
If tubing length is a critical dimension for your application, longitudinal shrinkage must be considered. In addition to shrinking in diameter, most heat shrink tubing products will also shrink in length. This is particularly important when using cut pieces or you have a specific length that you need to cover.
The amount of long shrink you can expect depends largely upon the shrink ratio and the manufacturing processing variables, but it is generally about 5%-10% of the original length.
Step 3: Choose the Appropriate Heat Shrink Material
So, you now understand your application and have chosen the appropriate size tubing. You are now ready to choose your heat shrink material. Often there are multiple products that will meet your needs, so it is important to also know the cost and availability of each option. This section will examine how to choose the right
Often there are multiple products that will meet your needs, so it is important to also know the cost and availability of each option. This section will examine how to choose the right material.
Polyolefin is the most widely used material for manufacturing heat shrink tubing, but there are many other speciality heat shrink tubings available in various fluoropolymers and elastomeric materials along with commercial options such as PVC.
Within each of these material families, there are many different compounds that have been designed to excel in certain environments and/or meet particular specifications.
Polyolefin Heat Shrink Tubings
Polyolefin is used widely as the base material for standard heat shrink tubing products, when this material is combined with other compounds, it is possible to produce bespoke materials that perform in certain ways:
Adhesive lined (or “dual wall”) polyolefin heat shrink tubing is a speciality product that has a wide variety of uses. This product is simply a standard polyolefin tube that has an inner-liner of adhesive that melts and flows at the same temperature at which the polyolefin tubing shrinks.
As heat is applied and the tubing is shrinking, the flowing adhesive fills voids and conforms to the underlying shape. This forms an environmental seal, protecting the underlying component(s) from moisture or other contaminants. An example of the use of adhesive-lined tubing is shown in the photo below:
Other Heat Shrink Materials
In addition to the products mentioned above, there are also other specialty heat shrink products available. These products all offer unique qualities such as extreme temperature resistance, exceptional chemical/fluid compatibility, and/or superior mechanical properties. Among theses products are:
Due to the enhanced qualities of these products, they are generally more costly than Polyolefin tubings. In some cases, the price differences are extreme. The diagram below gives you a simple, generic comparison of the price differences for a sampling of heat shrink materials:
Step 4: How to Use Heat Shrink Tubing
For a full, in depth explanation of how to install heat shrink tubing, please read the article below, it discusses various heating methods commonly used to shrink heat shrink tubing. It will also provide some handy tips:
The Raychem Corporation pioneered the development of heat shrinkable products back in the 1960’s. Raychem developed new types of plastics and elastomeric materials that were engineered to possess unique properties. This was achieved by modifying the raw material using radiation technology – a process that is now known as crosslinking (or cross-linking, x-linking).
The original crosslinking process worked by bombarding the raw material of the plastics with high energy electron beam radiation. The radiation caused the long chains of polymers to link together, altering the chemical structure of the material and increasing the molecular mass. Although the materials are usually crosslinked through the use of electron beams, it can also be achieved chemically using butperoxides, or moisture.
The process for making heat-shrink tubing is as follows:
The raw material is chosen based on its properties. The material is often compounded with other additives (such as colorants, stabilizers, etc.) depending on the application. A starting tube is extruded from the raw material.
The extruded tube is then taken to a separate process where it is cross-linked, usually through radiation. The cross-linking creates a memory in the tube.
The tube is heated to just above the polymer’s crystalline melting point and expanded in diameter, often by placing it in a vacuum chamber. Whilst in this expanded state it is rapidly cooled.
Later, when heated (above the crystalline melting point of the material) by the end user, the tubing shrinks back to its original extruded size.
As previously mentioned many of the material properties can be improved by crosslinking, for example:
Mechanical properties, such as tensile strength
Performance at higher temperatures, often with an increase in the melting temperature
Resistance to chemicals because of lowered solubility in organic solvents
Gas permeation reduction
Shape memory retention. Certain plasyic types (elastomers etc) may be crosslinked to a slight degree to give them “memory” – they will return to their original shape after being expanded.
Typical advantages of crosslinked materials include:
The most commonly used product categories for these enhanced wonder plastics are Single Wall Tubing’s, Raychem’s RNF-100 and RNF-3000 being the quality standard bearer.
Dual Wall Tubing’s with ATUM, HTAT and SCL leading the way in this category, and Elastomeric Tubing’s with RW-200 and DR-25 key products to the aerospace and defence markets.
This technology was originally developed in the 1950’s since then these basic product categories have been refined, enhanced and developed. Careful synthesis of materials provided products which could perform selective and very specific purposes. The addition of adhesives, shielding facilities, fibre and fabric materials ensures that the products are capable of performing in the most sophisticated installations.
PMG Company are uniquely placed, we can offer all the Single and Dual Wall products manufactured by Raychem/TE Connectivity either supplied TE Branded or where commercial constraints are paramount PMG can offer our own Plastronic brand equivalent:
Many people ask us to cross refer heat shrink tubing part numbers. If you have a description from another supplier or manufacturer and you would like to cross-refer this to a PMG Company product then please contact us.
If you already now the product description, then the table below gives a quick and easy cross reference guide:
Cross refer heat shrink tubing part numbers and product families
Heat shrink colours – What colours are heat shrink tubings available in?
When it comes to heat shrink colours, many people ask us the same question, “what colours are heat shrink tubing products available in?”. The answer is in fact quite complicated as the products are available in a wide range of colours; some standard and some that are specialist or bespoke.
The first thing to know is that that within the electronics industry, standard colours are internationally recognised as follows:
Electronics market Colour Code
The heat shrink colours listed in the table above will differ and are not controlled or standardised using a Pantone / RAL colour chart or similar colour scale, so between manufacturers (or even different batches of the same manufacturers material), it is not uncommon to find slight colour variation. In fact, this should almost be expected.
Colours supplied by one manufacturer in a certain product family or range should always be similar and within a few “shades”, but a different product material type from the same manufacturer, will probably be different. The key reason for this is that each material is made up of a mix of “ingredients” that has been specifically formulated to give the intended properties to the material. Because ingredients differ the ratio of colourant and the base material and property giving additives will differ, hence, the colour will differ. In simple terms, you could use the same amount of food colouring in two different sponge cakes, but if the flour is a different colour, you are likely to get a different shade of sponge at the end.
To view some of our heat shrink products and the available colours, please click here
When it comes to bespoke colours, many applications now call for the heat shrink tubing to be supplied to a specific Pantone or RAL colour (or another industry standard colour code), these are available but usually have to be manufactured specifically to meet the individual requirement. This is generally not a problem but the following considerations must always be made:
It is likely the MOQ (minimum order quantity) will be greatly increased.
The price is likely to be much higher than normal.
There are many ways to install heat shrink tubing, but the most common way is to use a hot air gun. The instructions below will explain how to do this.Before installation, it is extremely important to ensure that you have chosen the correct size of the product. When selecting the correct size tubing, you must consider the 80/20 rule – the chosen size should allow a minimum shrinkage of 20% and a maximum of 80%
Apply the heat shrink over the substrate and heat evenly around the tube, working either from the middle out or from one end to the other. Gradually heat the product ensuring that no air is trapped under the tubing until full recovery is achieved.
Heat shrink tubing will also shrink in length (longitudinally) so as the tubing shrinks in diameter it is likely it will also shrink in length.
Typically the longitudinal shrinkage is no more than 10%, although different products will have different tolerances. You must always take longitudinal shrinkage into consideration, especially when cutting the tube to length.
It is possible to minimise the longitudinal shrink by recovering the product at either end first and then working towards the centre. However, when doing this, care needs to be taken to avoid trapping air in the sleeve as this may restrict the product from recovering fully.
Alternately, if your application calls for the tubing to be more critically applied at a certain point (at one end for example), start the shrinking process in the critical area and work away, towards the other end.
If the substrate onto which you are applying the heat shrink tubing is made of metal or any other heat conductive material, take the time and care to ensure that that the object is pre-heated to avoid cold spots. These cold spots can counteract the heating process and cause the tubing to recover irregularly.
It may also be worth noting:
When preparing the heat shrink tubing for installation, it is essential that care is taken to ensure that any ends are cut and trimmed smoothly. Jagged or poorly cut edges can cause the tubing to split during installation.
Each product has a recommended optimum shrink temperatures that should be considered when setting the temperature of the heat gun.
During the shrinking process, you should always ensure that the workplace is well ventilated.
Here at PMG Company we have our own in-house cutting shop that enables us to supply cut lengths on the vast majority of our various tubings and sleevings. These products can be cut to almost any length you require and we can control the cutting very closely allowing for tight tolerances to be adhered to.
Customer requirements are becoming ever more complex and it’s clear that additional support is required. That’s why PMG Company took the decision to set up a range of additional services, key to the list is the cutting shop. It give you, our customers the flexibility you require.
If you need a braided or a heat shrinkable sleeving product in cut lengths or supplied cut to a specific tolerance, then look no further. Our ‘in house’ cutting shop is equipped with a range of specialised cutting machines including:
Hot knife cutters – for cutting braid and prevent fraying.
Standard vertical blade cutters – for accurate and clean heat shrink sleeve cutting
Tolerance cutters – for tight cut length tolerances, as well as controlled angle of the cut.
High volume commercial – used for high quantity runs
As a standard offering, our cut length service is available in bags of 100 pieces, 250 pieces, 500 pieces and 1000 pieces as standard. Obviously, for bulk enquiries or small batch runs, we are happy to help and the numbers can be customised where needed.
We have our own on-site and fully equipped printing facility that enables us to print on our full range of heat shrink tubing and identification products.
The complexity of electrical systems is increasing and the need to identify wires and cables is becoming more important. With this in mind, we set up a facility to provide bespoke services for customer printing and identification requirements.
Ranging from simple prints on continuous tubes (with or without scoring to allow the product to be torn and applied) through to individually printed and sequences pieces, our print shop can provide you with a made to measure solution.
Many customers simply require printing onto standard (and stocked) heat shrink tubing products. This provides a convenient and inexpensive additional service (there is a small fee). Options include:
As well as printing on standard heat shrink sleeves, we can also provide our full range of identification products pre-printed to your request.
With over 30 years of market knowledge and experience, we can also provide advice and expertise to help you choose the right solution:
A market leading distributor and component supplier, specialising in the design and supply of cable harnessing products.
As a provider off the shelf products and value added customised solutions, PMG are experienced and adept at working with design engineers to ensure that product selection, pricing, specifications and support levels all exceed our customers’ expectations.