How do you melt two pieces of plastic together?

Manufacture of plastic parts peru

This welding is feasible in thermoplastic parts. These linear polymers are susceptible to molding when they reach a certain temperature. Since they do not decompose when heated. Likewise, they can be joined together with heat and pressure. It cannot be applied to thermosetting plastics, because they are infusible and insoluble polymers. Once hardened, they cannot be softened again by heating.

Bonding of plastics takes place by softening of the areas to be bonded. For this purpose, the polymer molecules must be stimulated to acquire a certain mobility. This stimulation is performed by an external agent (heat, vibration, friction, solvent, etc.). Once the action of the external agent has ceased, the movement of the molecules decreases and an interlocked plastic structure is formed. In turn, pressure must be applied to achieve molecular interaction of the parts to be joined.

It is also worth mentioning that there are other types of plastic welding, which we have not detailed because they are not so widely used industrially or are more manual and less conducive to automation. More used in punctual moments for example in repairs, do-it-yourself and domestic works. They would be the following:

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Liquid plastic to make parts

Injection molding is a primary molding process for the sequential production of one or more three-dimensional thermoplastic parts. For this purpose, the plastic, possibly together with additives such as masterbatches, is dosed into the hopper of the injection molding machine and fed into the heated cylinder of the machine by means of a screw that rotates underneath. There, the components are melted, homogenized and conveyed to the closed machine nozzle at the end of the cylinder, where a melt cushion is formed. To inject the melt into the mold, the nozzle opens and the screw moves forward. The applied injection pressure ensures that the cavity is completely filled. As cooling starts there immediately, more melt is injected to compensate for the loss of volume during solidification. The tool opens as soon as the plastic has reached sufficient stability to allow the part or parts to fall out or be removed. At the same time, the machine provides the next injection cushion.

How to melt plastic without burning it

In general, polymer transformation processes are those involved in the conversion of granules or powders into products of practical use. There are several transformation processes, here at Todo en Polímeros we have decided to divide them into molding process for the processes that require a mold or extrusion process for those that require a die and the process is continuous.

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2. Forming: This is the stage of the process in which the melt passes from the plasticizing unit to the geometric space defined by the forming tool, which can be a mold or a die depending on the process.

By rotation of the screw the melt moves forward and accumulates at the front of the screw by means of a check valve in a volume known as a shot. A shot is the volume of material used to fill the mold cavity, compensate for shrinkage and provide a cushion to transfer pressure from the screw to the mold cavity. When enough material has been gathered, it is forced at high pressure and velocity into the cavity to form a part.

How to make plastic car parts

When adjusting a new or existing mold, there are a lot of variables that the fabricator has to deal with. However, there is one that gets immediate attention: adjusting cylinder zone temperatures. Operators don’t want to waste time waiting for the machine to warm up, so they generally adjust the zones to the desired temperatures as they adjust the mold and prepare for production.

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But the questions are: what temperature do you want the molten material to be, and what temperature profile in the cylinder zones will get what you want? Most would agree that having the material at the correct melt temperature is an important factor in making quality parts have stable, trouble-free production.

Machines can have four or more temperature zones in the cylinder, but the basic zones are: feed, rear, middle and front. You must also properly control the body and nozzle tip (Fig. 1). The processor starts by selecting a target melt temperature. If this is a new material or grade for you, check what the manufacturer recommends.