For many types of fans such as axial fans, wire guards are an important part. The protective grids increase the safety and protect the interior against intake of dirt. Wire guards are mounted on the air intake and the air outlet, also known as the suction side and pressure side.
In the factory of Blok’s Draadvorm, wire guards are manufactured on a daily basis. We produce to the specific needs of our customers and have seen wire guards in many different sizes and shapes leave our production facility. From very large to very small, round, oval or square and flat or three-dimensional, we commit to the challenge to create a perfectly adequate grid for your product.
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Our wire guards are manufactured according to the latest safety standards. This includes passing the so-called finger proof, a test that determines the maximum distance between the individual bars of the grid at no more than 8 mm. This safety standard will prevent personal injury when using fans. To guarantee this accuracy, we use a welding mold in the production process of the various protective grids we make. That’s how we make sure all your products are identical to each other. The welding techniques we use to produce wire guards are resistance spot welding and intermediate-frequency welding. Intermediate-frequency ensures an even stronger weld.
Some of our welding molds.
Ventilation grids, what material and what finish?
Most of our ventilation grids are made of galvanized steel and finished with a powder coating. Galvanized wire has a corrosion-resistant layer of 20 µm (micrometer) and the powder coating adds 80 µm to give a total of 100 µm. This will significantly increase the lifespan of the wire guards. It is important to degrease and phosphate the wire guards prior to powder coating. This pre-treatment ensures the powder to attach much better to the surface area. We have a special washing machine in our factory for degreasing and phosphating our wire products. This machine reuses all the detergents and is environment-friendly.
Many of the wire guards we produce end up being placed in stables or other damp areas such as greenhouses. Our fan guards are also used in food storage centers, where they are placed on some of the biggest fans we have seen. Under these conditions an even thicker corrosion resistant layer may be desirable. Therefore, we can also apply a PPA (polymer) finish instead of a powder coating. The total thickness of the protective layer can be set between 150 and 250 µm.
Furthermore, large fans often are part of climate systems and industrial condensation systems. It is precisely in these applications, where only the best is good enough because the conditions are the toughest, where wire guards with a PPA finish prove their added value.
We can also make stainless steel ventilation grills. The destination of the fans is crucial in the choice of material and finish. In stables (ammonia) and coastal areas (salts) one often opts for stainless steel 316. The cost of this material is, however, relatively high. In addition, stainless steel always needs to be pickled and cleaned with ultrasonic technology, which increases the cost even further. That is why, even under these conditions, we prefer to use galvanized wire with a PPA finish. This is simply cheaper and gives an equally thick or even thicker corrosion resistant layer.
Video: our DLM at work. A fully automatic welding machine, custom built for Blok’s Draadvorm.