Electrically conductive and colorable for ATEX

Electrically conductive and colorable for ATEX

Safety in explosive atmospheres has been regulating for years by the European ATEX Directives, which identify, among many other parameters, the maximum surface electric resistivity below which the accumulation of electrostatic charges is not observed.

The problem is particularly acute for plastic products, on which the formation of high electric potentials may cause dangerous discharges as being a potential ignition source for fire and explosion.
The traditional solution for antistatic compounds is the use of carbon black, graphite, and carbon or steel fiber based fillers.
These approaches are all valid, but strongly limit the image of the finished product, which is available only in black.

LATI’s wide range of electrically conductive products includes LATIOHM PD02 grades, in which electrical resistivity is reduced by the presence of special polymers ensuring, in addition to antistatic properties, colorability without the need of special painting.
A modular torch made of yellow-colored LATIOHM 62-08 PD02 G/35 in compliance with ATEX was developed and marketed for professional use.

Safe and lightweight, but sturdy due to the 35% glass fiber reinforcement, the LATIOHM torch is composed of different interchangeable parts for a very flexible and varied use.

The base resin selected for this project is PA6, a polymer that is chemically resistant to oils, greases, and hydrocarbons, very fluid and versatile, suitable for the molding of aesthetically pleasing parts.
In the choice of formulation, LATI distances itself from solutions with antistatic properties limited to a few weeks, since PD02 compounds permanently ensure a resistivity of less than 10^9Ω.

Despite the presence of glass fibers, pigments and dissipative polymers, all LATIOHM PD02 products are suitable for the manufacture of parts of even large size and thickness without the need of special equipment or measures.

Automotive and thermally conductive compounds

Automotive and thermally conductive compounds

Weight reduction is an essential requirement for automotive and transports in general.
It is in this context that the project of metal replacementwas developed by a major multinational company operating in this sector for the manufacture of a vacuum pump housing (EPV pump) for the brake oil circuit.

This product is required to perform a number of structural tasks, and is the result of a significant sum of functions, as evidenced by the many connections on the cover.
The area of use is the underhood, close to the engine, which is a chemically challenging environment with temperatures ranging from -40°C to +120°C.

As in all pressure circuits, maximum dimensional stability is an essential requirementto avoid pressure losses to be compensated with seals, and the risk of pump malfunction.
In this case, the body should also provide high thermal conductivity to allow for the best braking system operation.

LATI accepted the challenge and developed the LATICONTHER 62 GRG/500, a PA6-based compound with 50% graphite and short glass fiber reinforcement.
With a thermal conductivity of 15 W/mK, this compound was chosen to mold covers featuring not only mechanical strength and dimensional accuracy, but also able to remove part of the heat generated by the hydraulic circuit drives.

The pump body made of conductive thermoplastic material successfully passed even the most feared stumbling block to metal replacement projects, i.e. fatigue strength testsunder operation to determine product reliability over time. Ease of molding, possibility of production waste recovery, and the absolute compliance with the most stringent regulations on the protection of human health and the environment made this a winning project also from the point of view of the final product cost.

Conductive compounds temperature cools down

Conductive compounds temperature cools down

Between reality and false myths, here are some recommendations to take best advantage of the properties of thermally conductive compounds.

Almost ten years after their introduction to the market, the success of thermoplastic compounds with improved thermal conductivity can be considered as established. Despite the inevitable initial mistrust and difficulties connected with the use of such materials, today many manufacturers of technical compounds include in their range at least one series of grades for injection moulding items requiring a better heat removal.
However, the approach to these new proposals is not always correct, especially by users accustomed to historically proven materials, primarily aluminium or copper. So some “myths” have to be dispelled not to incur common design errors.

Main evaluation mistakes
A first mistake is to expect the same thermal performance of metals.
This is a wrong assumption, as many successful applications showed that metals, in terms of heat exchange, are often oversized, and the same results can be reached by thermally conductive compounds with one-tenth thermal conductivity. This is especially true in the natural convection regime, i.e. when heat extraction is not carried out by forced ventilation. The second typical error is to continue to think about “standard” geometries – e.g. for heat sinks – i.e. designed for a good heat transfer, but always using metals.

A new and more flexible mindset is to be entered into, which allows to understand that thermoplastic compounds are completely different materials, in particular with regard to their compositional inhomogeneities resulting in an physical anisotropic behaviour.
Not considering this fact and treating plastics in the assumption that they behave like metals, may lead to significant design errors, sometimes ending in the failure of potentially viable projects.
For this reason, it is extremely important that the most intimate properties of these materials are understood, “tamed” and capitalized on, especially in the design phase.
In addition, requirements are not limited to thermal performance.

Conductive compounds temperature cools down

There are, in fact, aesthetic constraints imposed by marketing and product designers, as well as electrical and mechanical properties. The development of increasingly efficient compounds even from this aspect, as well as the freedom of design, flexibility and efficiency of operation offered by these materials, are consolidating their increasing success in the most advanced technology sectors…

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The new SPDs by ABB for the surge protection

The new SPDs by ABB for the surge protection

ABB’s expertise in electronics and LATI’s expertise in the world of special thermoplastics have given rise to a new product for the protection from transient voltage surges and lightning: PM EP 15 15-275 RES is a pre-wired protective device (SPD or surge protection device) featuring modern design and small dimensions.
Designed for use in control housings and compact power supplies, the new SPD is ideal for use in the new LED systems, especially those dedicated to public spaces, such as parking lots and parks, road signage and lighting, decorative lighting etc.
In fact, these are the light sources that are mostly affected by power grid disturbances, specially industrial or natural (lightning) surges that are captured and amplified by the long electrical connections with power supplies.

Voltage peaks may easily cause failures in LED units if not stopped, thus resulting in service disruption and often expensive and complex maintenance requests.
So here is the perfect ABB solution to be combined with residual current circuit breakers and fuses to preserve the integrity of the systems to be protected.

Both the envelope and terminal blocks of PM EP 15 15-275 RES are made by injection molding of LATAMID 66 H2 G/25-V0HF1, a PA66-based thermoplastic compound formulated by LATI to be self-extinguishing and structural thanks to a 25% glass fiber reinforcement.
The performance of the V0HF1 grade is appropriate from both the structural and flame safety point of view as confirmed by UL and VDE certifications attesting the excellent self-extinguishing properties, as well as the resistance to incandescent wire with GWFI = 960°C at 1 mm.

ABB’s choice fell on the LATI compound not only for its technical performance and the versatility of the material, but also for its total safety and respect for the environment, backed by a RoHS compliant formulation completely free from halogenated flame retardant additives.