Usually Injection Mold Designers Design Only Injection Moulds
In a Blow Molding process a hot tube of molten plastic is extruded via a die. The hot tube of molten plastic is suspended in mid air before the mold closes, while the tube is within mid air it can be stretching and cooling.
With Injection molding the plastic is contained in the barrel of the machine and also the runner with the mold, the operation is controlled precisely until the part is ejected from your mold.
With Blow Molding there is precise control in the machine however the process has elements which can be challenging to control.
The fundamental difference around the molded part is always that Injection molded parts molded in one shot possess a single wall while Blow molded parts have to be a whole shell with an air gap inside. A simple blow molded part will be for example a shampoo bottle. A far more technical blow molded part is actually a bottom shell lawnmower seat hollow on the inside, this type of lawnmower seat might have many shapes and cut out's with a few performed in the molld.
When making an Injection Molded part the typical rule is to conserve a uniform wall thickness as much as possible, this is controlled by the mold and mold design. Wall thickness on a blow molded part is controlled by the machine while also the mold design does play a role within the wall thickness of the finished part. When designing a blow molded part many shapes are possible but blow ratio's need to be maintained. A hole is required on a blow molded part as the plastic is expanded in the mold with air pressure although some parts can be made using trapped air to blow.
Apart from a sprue in a typical Injection mold there isn't any waste actually on a Hot Runner mold there is no waste. A blow molded part does have waste for the reason that plastic trapped between your mold comes with excess away from molded edge. This molded edge on a blow mold is called pinch edge or nip edge. It has a cutting effect to separate the waste plastic from the molded part.
Designing a blow molded part needs many considerations as well as an knowledge of the operation is vital. Generally a shape cannot be blown with reasonably uniform wall thickness unless the width of the cavity is equal to or lower than the depth of the cavity. Another consideration is sharp corners, the only place a sharp corner is allowed on a blow molding is the parting line.
Usually Injection Mold designers design only Injection Moulds and the same usually applies to Blow Molds because the mold designs are so different. An item designer working on plastic parts should know each process and be capable of designing a part that will work for the method chosen. It is not possible to have a part design which can be blow molded or Injection Molded. It needs to be one or other and a good designer will know which process to choose.
With Injection molding the plastic is contained in the barrel of the machine and also the runner with the mold, the operation is controlled precisely until the part is ejected from your mold.
With Blow Molding there is precise control in the machine however the process has elements which can be challenging to control.
The fundamental difference around the molded part is always that Injection molded parts molded in one shot possess a single wall while Blow molded parts have to be a whole shell with an air gap inside. A simple blow molded part will be for example a shampoo bottle. A far more technical blow molded part is actually a bottom shell lawnmower seat hollow on the inside, this type of lawnmower seat might have many shapes and cut out's with a few performed in the molld.
When making an Injection Molded part the typical rule is to conserve a uniform wall thickness as much as possible, this is controlled by the mold and mold design. Wall thickness on a blow molded part is controlled by the machine while also the mold design does play a role within the wall thickness of the finished part. When designing a blow molded part many shapes are possible but blow ratio's need to be maintained. A hole is required on a blow molded part as the plastic is expanded in the mold with air pressure although some parts can be made using trapped air to blow.
Apart from a sprue in a typical Injection mold there isn't any waste actually on a Hot Runner mold there is no waste. A blow molded part does have waste for the reason that plastic trapped between your mold comes with excess away from molded edge. This molded edge on a blow mold is called pinch edge or nip edge. It has a cutting effect to separate the waste plastic from the molded part.
Designing a blow molded part needs many considerations as well as an knowledge of the operation is vital. Generally a shape cannot be blown with reasonably uniform wall thickness unless the width of the cavity is equal to or lower than the depth of the cavity. Another consideration is sharp corners, the only place a sharp corner is allowed on a blow molding is the parting line.
Usually Injection Mold designers design only Injection Moulds and the same usually applies to Blow Molds because the mold designs are so different. An item designer working on plastic parts should know each process and be capable of designing a part that will work for the method chosen. It is not possible to have a part design which can be blow molded or Injection Molded. It needs to be one or other and a good designer will know which process to choose.