When is it worth using virgin or recycled resin? (Part 2)
7 tips for selecting a good supplier at a technical level
1) Industry and / or trade?
Some suppliers despite having their business name as industry and trade, are often just trades. Avoid this type of company to buy recycled material, because you will be putting an intermediary in the purchase that will need to resort to the real recycler if you have problems with the material, which will generate a good waste of time.
Be wary of recyclers who do not keep a good stock of grinding or scrap, the recycler needs materials to assemble formulas and correct their products quickly, which is not possible if it tries to "simulate" the deployment of just-in-time . The idea of maintaining low inventory levels is only advantageous for transformers, not for recyclers, remember that!
3) Quality control
A good recycler should have a laboratory with the following equipment:
FOR POLYAMIDES: muffle, humidity determiner, melting point determiner, laboratory injection molding machine, impact resistance machine.
FOR OTHER PLASTICS: laboratory injection molding machine, impact resistance machine, flow rate, humidity determiner and colorimeter / spectrophotometer if working with colors.
Some companies do not have a laboratory or equipment and even then invent or copy reports that do not fit the reality of the product, be careful!
A plastics analysis lab
4) Technical support
Check the level of technical knowledge of the sellers, sometimes you may need simple adjustments to the material such as load increase, impact modification etc and in that case you need someone with that knowledge to give you support.
5) Contamination control
Verify if the recycler receives contaminated materials (with other plastics) and what methods are used to perform decontamination. The company must have trained personnel to identify quickly the various types of plastics through burning, cutting, weight etc.
Some recyclers already buy their raw material, ready to be granulated, this can make it difficult to check if they do not have a laboratory or if they do not test the raw material, since it is more difficult to carry out a visual inspection under these conditions. The ideal thing is that the recycler itself grinds the parts and / or residues, removing from the process those that are contaminated.
6) Variety of products
Possessing several variations of a product can indicate a recycler who has complete control over its production, being able to modify characteristics of the material according to the needs of the client.
The recycler has the following products:
ABS A1 ABS - extrusion abs
ABS A2 BLACK - medium flow abs for general use
ABS A3 BLACK - high flow abs for injection of thin wall parts
In the above example he is supposed to be able to control the flow rate of ABS, but what if he had only one resin called ABS BLACK? We could suppose that the ABS received from any source by the recycler would be called by the same name, being able to have any melt flow index, thus having a lower quality.
7) Production capacity
Recycling can be a time-consuming process where an extruder can produce from 50kg / h to over 500kg / h. It is recommended to check this question to make sure that the supplier is able to attend to you without delays in the orders due to bottlenecks in the production, even because it happens that the supplier "does not remember" it at the time of selling!
In what applications can I use recycled plastic?
We can say, generally speaking, that aesthetic parts must use virgin plastic while mechanical parts can use recycled, but we will delve into this subject now giving some examples of parts.
A) Mirrored parts
Generally, they are electronic housings made of ABS. It is recommended to use new material in this type of part, because eventually the recycle may contain some impurities such as rubber, paint and metals, all in the form of tiny particles but that end up being well visible to the naked eye in flat and mirrored pieces.
B) Carcasses of textured home appliances
In this case the recycled material can already be used without problems since the flow of the polymer on the surface of the mold occurs without any differences in visual appearance compared to the new resin.
C) Automotive parts
Inside a car there are several pieces made with recycled plastic, mainly polyamides (mechanical parts) and ABS (internal parts).
The fact that an automotive part is subjected to high temperatures and contact with oil and other fluids does not reduce the possibility of the application of the recycled plastic, even though there is no significant loss of chemical resistance or heat during recycling.
D) Anti-flame parts
Recycled plastics can also receive anti-flame additives and get the same performance from a new plastic having a great cost-benefit.
E) Medical area
Use only new material.
(F) Toys, household goods
Regardless of the use of new or recycled material, it is recommended to ask the supplier for a report proving the absence of heavy metals, common in the formulation of pigments in some countries. Being in compliance, recycling can replace the new one in these applications as well.
Beware of hazardous substances
Unlike virgin resin, recycled has several substances that are not part of its monomers in its composition. Some of these substances such as cadmium and lead (heavy metals) are considered dangerous and are prohibited in certain countries, especially in the European Union through the RoHS directive.
For commercialization of materials in these countries or even where there is no legislation on the subject, it is recommended to send the material to a laboratory that performs X-ray fluorescence spectroscopy analysis to detect the substances present.
Have you seen the first part of this article?
HARPER, Charles A.; PETRIE, Edward M. Plastics Materials and Process: A Concise Encyclopedia. Hoboken: John Wiley & Sons, Inc., 2003.
WIEBECK, Hélio; HARADA, Júlio. Plásticos de Engenharia: Tecnologia e Aplicações. São Paulo: Artliber Editora, 2005.
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