Hot glue gun
The hot glue gun , often just called glue gun , is a tool for processing hot melt glue .
The first patents come from William R. Meyers and Albert S. Tennent ( 1949 ), Hans C. Paulsen ( 1965 ) and George Schultz ( 1971 ). Industrial hot glue guns were first sold in 1973 by the 3M company in the USA under the name "Polygun" (until 2006). The inexpensive stick glue guns for general use, which are widespread today, were introduced to the German market in 1975 and 1976 by Bühnen GmbH & Co. KG from Bremen .
function
The mostly bar-shaped adhesive ( hot-melt adhesive ) is introduced on the back and melted inside the gun by an electric or fuel gas- operated heater.
By operating the transport lever ("trigger") the plastic rod is pushed into the melting chamber, the already liquefied plastic located there escapes from the front nozzle.
Simple and small glue guns do not have a transport mechanism; here the stick of glue (“candle”, “stick”, “glue cartridge”) is pressed in with the thumb.
In addition to the mechanical devices, there are also devices that convey the adhesive from a small tank or cartridge through the nozzle with air pressure.
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Hot glue sticks (glue sticks)
Sticks with diameters of 11 mm (11.2 mm, 7 ⁄ 16 inches) and 7 mm (7.2 mm, 9 ⁄ 32 inches) are widely used . Devices for adhesive sticks with a diameter of 12 or 18 mm are less common. The rods are mainly made of EVAC ( ethylene-vinyl acetate copolymer , formerly EVA), less often of PO ( polyolefins ) and PA ( polyamides ). The smooth sticks have a round cross-section, are around 60 to 195 mm long and are inserted individually. Occasionally, brand manufacturers offer devices with flat-oval adhesive sticks, which are usually not compatible with each other.
Hot melt adhesive guns with electro-pneumatic propulsion can basically use any hot melt adhesive in almost any form (granules or blocks) thanks to their tank .
hazards
Glue guns heat up during operation, especially in the front area near the nozzle, so that burns are possible if they come into contact with the skin.
Liquid hot glue is hot up to 200 ° C and causes burns if it comes into contact with the skin . The still liquid hot glue cannot be completely removed from the skin. It should therefore first be solidified by applying cold water.
application
The heating-up time of glue guns for 7 mm glue sticks is around two minutes, for 11 mm sticks it is around five minutes. The heating element has PTC properties. This means that the heating output is adapted to the requirements to a certain extent. However, by rapidly advancing the adhesive rod, the melting chamber cools down and the outflow of the adhesive slows down considerably.
A continuous operation of inexpensive devices without temperature control is usually limited to a very low adhesive throughput, since the melting chamber cools down with a larger advance and slows down the further advance. This reduces the area of application to point gluing or linear gluing of poorly heat-conducting, flexible materials that can gradually be covered with the adhesive and pressed down. If larger quantities of adhesive are required, as is often necessary with material that conducts heat well and cannot be preheated, then it can be ejected in batches at certain intervals. In between, you have to wait until the melting chamber has heated up again.
In devices without electronic control, the melting chamber heats up if there is insufficient throughput of adhesive until it becomes so thin that it drips out of the nozzle even without advancing the adhesive rod. The hot glue gun should therefore only be used on insensitive surfaces and placed with the nozzle pointing upwards.
Temperature-controlled devices allow a significantly higher heating output without having to worry about the device overheating during work breaks. These devices enable a controlled, continuous throughput that can be varied over a wide range.
Due to the rapid cooling of the liquefied adhesive, only small-area jobs can be carried out with simple glue guns. The adhesive solidifies much more quickly on materials with good thermal conductivity than on paper, plastics or wood. To bond objects made of materials that conduct heat well, such as metal, stone or glass, it is advisable to preheat them. This improves the adhesion of the adhesive and allows a longer processing time.
Some hot glue guns with pneumatic feed allow the glue to be sprayed in an air jet, which makes it possible to apply it over a large area.
Private application
The simple handling and the favorable purchase price led to a wide spread of these devices in the private sector. They are used, among other things, for handicrafts or minor repairs in the household .
Commercial use
Commercial hot melt glue guns are often referred to as “stick guns” and “mechanical or pneumatic hot melt glue guns ”. These are particularly widespread in the areas of floristry and interior design . Further applications of handheld devices are e.g. B .:
- Automotive industry
- Furniture industry
- Manual packaging production / cardboard gluing
- Electrical industry - anchoring of cables and electrical components
- Display manufacturing
In contrast to most do-it-yourself guns, professional devices often have a temperature control (40–250 ° C) so that different adhesives can be used and the viscosity of the liquid adhesive can be adjusted. It is often also possible to use interchangeable nozzles with a narrow, wide or flat outlet opening. Some devices can be switched from a compact adhesive flow (linear or punctual application) to spray operation by supplying additional compressed air through a special nozzle.
Web links
Individual evidence
- ↑ [1] US patent US2567960
- ↑ [2] US patent US3204828
- ↑ [3] US patent US3587930
- ↑ Important Change Notification ( Memento from February 1, 2013 in the Internet Archive ) (PDF; 28 kB) - Information on the renaming of the Polygun in ScotchWeld from February 1, 2006 by the 3M company
- ^ [4] Company history of the Bühnen GmbH & Co. KG years 1975/76