How Can You Tell The Quality of Your Rubber Sheeting?
Rubber sheeting comes in many different types and forms. It is available from a wide range of manufacturers and vendors both within the UK and across the globe. But when there is such a wide range of choices and prices available, how can you tell that you’re actually getting the quality rubber sheeting you think you are?
First of all, we need to assume a few things; that the technical personnel within an organisation have been involved in specifying the correct material i.e. neoprene, nitrile, viton, etc. We also need to assume that the purchasing department have developed and procured against a proper buying specification. In a nutshell, these measures will ensure that you are buying the product you require. There are processes in place to make sure you get the right product of suitable quality.
If your company is happy to buy lesser quality rubber sheeting to glean absolute rock bottom prices, then this article may not be the best advice for you – on the other hand, it may help you in the long run to get a better product.
OK, so your nice new shiny rolls of rubber have arrived and you are keen to get on with processing them to fulfil your new customers’ order. But, there’s a stink going on! First things first – cheap rubber rolls will give off an awful smell, similar to burnt rubber and very pungent. Some people believe that this is how rubber smells but in actual fact; this is just what cheap rubber smells like.
The bad odour is coming from the low grade reclaimed rubber that has been used to make the rolls. It’s made from old rubber articles that have been ground down into a powder, then incorporated back into a formulation. Its technical characteristics are far inferior to the virgin polymer it has replaced with its only purpose being to make the product cheap.
Tip number 1: follow your nose!
Now, let’s get a little more technical. The ‘recipe’ of the ingredients that are used to make rubber sheeting is called the ‘formulation’ and all formulations have a ‘specific gravity’ or ‘SG’. Simply put, it’s similar to a density measurement and each type of rubber will have a typical SG. This varies according to measurements like hardness.
Whilst it’s OK for the SG to vary, it can also be a giveaway for poor quality rubber. Cheap fillers are mixed in make the SG higher and often replace higher quality and lower SG materials like polymer. For example, a good quality nitrile rubber might have an SG of 1.26 whereas a poor quality nitrile rubber might have an SG of 1.42. Again, the fillers that have been added don’t give better compression, tensile or other readings. Their only purpose is to lower cost at the expense of performance.
Tip number 2: compare SG’s.
Relating to the use of extending fillers in rubber sheeting, there’s a little hack you can use to check. Scratch the surface of the rubber sheeting with your nail. If you see a white scratch mark appear, then the chances are that it has a lot of cheap filler in it. This filler is quite often chalk so what you are seeing is the chalk being scratched from the surface. Likely not very reassuring for you, the customer!
Last in our series of tips is making an assessment of the sheeting’s physical properties. As alluded to already, if sheeting is made from low quality ingredients and especially has too much filler at the expense of polymer then its physical characteristics will be very poor.
Standard measurements for physical attributes include: tensile strength, tear strength, elongation at break and compression set. If you have a testing laboratory (or access to one), you can put your sheeting through its paces or at least be able to make a comparison of datasheets. You will find from your own results that higher quality materials will give better physical characteristics. Simple!
Tip 3: compare physical properties
In rubber sheeting like everything else in this world, you get what you pay for. It’s not our role to say what is and isn’t the right grade for every application, but hopefully now you’ll be better equipped to judge what you are getting and make changes if you feel necessary.