If you are recycling plastic goods or handling virgin materials, making a product free from metal contaminants is much more important today than ever. Trends to thinner walls, tinier hot-runner nozzles, and more pricey and sophisticated machinery and tooling mean that even the smallest piece of tramp metal can cause costly problems.
Processors often do not recognize the significance of Baggage Screening X-Ray Machine. Even virgin material can acquire metal contaminants at various stages of manufacturing and transportation, right up until the second it enters the throat of your own molding or extrusion machine. Contamination can range from tiny particles worn off by equipment abrasion to entire nuts or bolts loosened by vibrations in processing machines. There’s even the human factor: Inevitably, items such as coins, pens, and paper will occasionally fall into the merchandise stream.
For this reason, metal-detection technology can be used throughout the plastics industry to guard processing equipment and to ensure product purity. Metal detectors keep your product under strict surveillance at all times and prevent unnecessary machine downtime and costly maintenance.
Whenever we speak of “metal detectors,” some processors may believe first of magnets. These are used effectively before the metal detector for capturing ferrous metals. Less familiar to a lot of processors are electronic detectors for all types of metals. These are active devices that actuate a valve or any other device to reject the contaminated material.
What’s more, electronic metal detectors could be monitored remotely from a pc. This capability offers a record of where and how frequently contamination takes place in your plant. Such valuable data may help you compare the purity of different vendors’ resins or diagnose excessive machine wear.
How metal detection works – The two main basic varieties of metal detectors:
Single-coil systems – Each time a metallic particle falls from the high-frequency electromagnetic field, an eddy current is induced in the particle, thereby removing energy through the coil system. As a result the utmost amplitude in the coil’s vibration decreases. More energy will be supplied to increase the amplitude back to maximum level. This disturbance in the coil’s vibration is detected by the electronic circuit as signaling the existence of a metallic particle.
Balanced-coil system – Single-coil systems provide cost-effective solutions for simple, “down-and-dirty” applications. These systems are simpler to setup, however they cannot compensate for products which may be slightly conductive, because of the actual existence of moisture, acidity, or additives like carbon black.
Balanced-coil systems offer product-effect compensation that suppresses false signals brought on by the item. The benefit is always to prevent rejecting perfectly good material. Analog versions need the operator to manually reset the compensation as material moisture content or some other variable changes. Newer digital versions may be preset to self-adjust for different products or an array of moisture content or some other variables within a product.
Making sensation of sensitivity – Electronic metal detectors are high-tech, sensitive devices that must definitely be handled with a certain amount of care. Excessive vibration from motors, chains, as well as other nearby equipment may cause a detector to emit a false signal and reject good material.
You shouldn’t must sacrifice good material for accurate detection and rejection. As well as product-effect compensation, state-of-the-art Metal Detector Security Gate offer adjustable sensitivity and positive speed control to reduce the volume of material lost.
Maximum sensitivity of any detector determines the minimum size of metal particle that it can sense. Smaller particles can slip through, and this factor is essential to choosing the proper detector to have an application. Maximum sensitivity is measured by loading a sample of resin with steel spheres and utilizing the measurement in the midst of the coil, where the sensitivity is lowest. Steel spheres are utilized because they have a uniform, defined size, meaning that the measurements are repeatable. Also spherical particles are definitely the most difficult to detect because of their relatively low surface.
All metal separators are not equally sensitive. True sensitivity depends on the size of the search coil. Smaller the search coil, the lesser the metallic particle which can be detected with maximum sensitivity. A good guideline to bear in mind is the fact normal sensitivity is approximately 1% from the diameter from the coil. Based upon the sensing aperture, innovative pbgavn are capable of detecting contaminants as small as .4 mm.
Sensitivity can also be associated with the composition and form of the fabric. Although electronic all-metal separators will detect ferrous particles, stainless-steel, lead, aluminum, bronze, tin, and a lot more, these are most sensitive to ferrous particles. This is because metallic particles are detected by means of eddy currents, and the larger the eddy current the higher the sensitivity. Eddy currents on the surface of ferrous particles are more than those generated on the surfaces of aluminum, bronze, or copper particles, meaning the sensitivity of ferrous particles is higher than the second. What’s more, eddy currents from metallic particles are just effective on the surface, so the larger the surface, the higher the sensitivity. Because of this flat metallic particles, or particles with irregular shapes, are much easier to detect than spheres.
Another feature provided by Deep Target Waterproof Metal Detector is referred to as positive speed control. Due to differences in bulk density, metal particles may well not travel by way of a pneumatic conveying line in the same speed as the resin itself. Positive speed control senses the particular conveying speed of the metal contaminants and automatically adjusts the open duration of the rejection valve in order to get rid of the metal with a minimum of resin loss.
Junhong Electronic&Technology (Dongguan) Co., Ltd is a professional manufacturer since 2005, specialized in R&D of security detection technology. We have various of products range: Walk through metal detectors, hand held metal detectors, X-ray luggage scanners, X-Ray Body Scanner, Underground Metal Detector, Industrial Metal Detector, Checkweigher, Infrared Body Temperature Detection System; Explosives Detector, Under Vehicle Surveillance Systems; etc.
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Address: No.23, Xintian street, Baizhoubian, Dongcheng district, Dongguan city, China