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ENVELOPES
Careful orientation of the envelopes ensures the valves are in the correct position
Cooling envelopes between cures ensures a longer life
Avoid poor storage in conditions that will lead to premature failure of the envelope
Getting the Best Out of Envelopes
to further damage and misuse. “Envelope rubber is tough but it is still subject to damage from poorly maintained equipment and mishandling; so sharp edge and poor practice can lead to life limiting damage.”
There is a theme starting to run through these issues, and it is followed through on Sandberg’s next couple of points, lack of training in how to properly deal with the envelopes and improper repair of lightly damaged envelopes.
These points all reduce the life of an envelope and increase costs. So, Sandberg says, key to minimising envelope costs is a process of proper envelope management that
inspected at regular intervals. The easier they slip off and on the casing the less likely they are to be damaged. It is also a good idea to rotate the envelopes in the spreader. In a busy operation, there is a real possibility of the tyre and envelope being loaded onto the spreader in the same way every time. That creates weak points. So, by rotation those weak points can be avoided. Also, by switching the envelope around both sides get used and that again avoids repetitive stretching from weakening the envelope.
“Inspect envelopes on a regular basis and have sufficient stock that you do not overuse the envelopes. They should also be inspected for
Robbins LLC is a leading player in the manufacture of products for the retreading sector. The factor y at Muscle Shoals, Alabama, is home to the manufacturing process and the products proudly state that they are “Made in the USA”.
Sales Manager, Hugo Sandberg believes that retreaders should always get the best from the product that they use, and envelopes are a consumable with a cost that can have a real impact upon profitability in retreading. At a time when production costs have to be managed very carefully to
valves.
Sandberg says. “Envelopes are key to the retread process, and aside from rubber and labour that form the largest expense for a typical retread facility.”
In order to make the best use of Robbins’ products (and those of any other supplier) it is important to understand the potential issues that retreaders come across. “Firstly, and almost understandably, is the lack of stack at the retreaders’ facilities. They may be reluctant to carry more stock than they think they need, or perhaps they have lost stock
considers process; inventor y; housekeeping; storage and inspection. These points all address the issues identified in shortening envelope lifespan.
If the level of envelope stock is optimised, allowing for cooling times and cycling of stock, then looking at how the envelopes are used is the first step in improving efficiency. “Keeping the envelopes fresh is key,” says Sandberg. “They need to be properly lubricated and
blemishes and damage, particularly to the edges of the rubber. “However, it is not just the rubber that needs inspection. Also check the equipment that comes into contact with the rubber – J-hooks, storage bins and spreaders - remove any sharp edges and keep the envelope area free from discarded staples.”
All this makes sense and should really be second nature to retread shops but none of these points can
help retreaders compete in a modern market, Sandberg says that envelope and tube management is critical to extend their useful lifespan and reduce lifetime costs.
Robins produce a wide range of solutions for the retreader, including inner and outer envelopes, OTR envelopes, hand built envelopes, unitubes, curing tubes, wicking pads, repair kits, envelope lube and a wide range of
through wear and tear and just have not replaced damaged tubes because they ‘have enough’ to keep things rolling. However, a low stock of envelopes leads to improper cooling times between cycles, so the rubber never gets a chance to cool down and is continually expose to high- temperature levels.
“Hand in hand with this overuse at high-temperatures is often a lack of suitable storage, which can lead
68 Retreading Business