| Have you ever noticed that the vast majority of | | | | moulding tools are very expensive to manufacture |
| plastic promotional pens are tapered? That is to say, | | | | because the tapered cavities are difficult to machine |
| wider at one end than the other. Apart from | | | | with perfect consistency. This is partly because it is a |
| aesthetics, there is only one explanation for this and I | | | | slow and difficult process to machine accurately inside |
| will now discuss the technical reasons for this. | | | | a narrow and deep hole that will eventually form the |
| All high quality plastic pens are injection moulded in | | | | cavity for the promotional pen barrel. A simple |
| steel cavities that form part of a device known as a | | | | solution is to have the tool split down the middle and |
| moulding tool or 'die'. The inside walls of these | | | | the mould is in two separate halves. With this |
| cavities are perfectly regular in terms of surface | | | | method of manufacturing there is no need for a |
| finish, they may be polished, textured or striated. | | | | taper as the mould simply opens and the promotional |
| The plastic material (polymer) is extremely hot when | | | | pen barrels fall out. The downside to this is a seam |
| injected into the cavities and must be cooled down | | | | will be visible down the sides of the promotional pens |
| before the promotional pen barrels are ejected. Time | | | | and this can detract from the aesthetics. If the items |
| is money in business so the faster this whole cycle | | | | are to be printed as a logo pens or personalised pens |
| becomes, the higher the production rate and the | | | | the seam can cause printing problems as the printed |
| more cost effective, or profitable, the promotional | | | | image ends up being smudged as it tries to cover the |
| pen becomes. To help speed up the whole process, | | | | seam. |
| the mouldings are rapidly cooled by high pressure cold | | | | This process is therefore only used on cheaper |
| water that is injected into channels surrounding the | | | | promotional pens, or pens whose shape are so |
| cavities. | | | | complex they could not be removed from the |
| These channels are sealed from the cavities so there | | | | cavities by conventional means. Metal pens are also |
| is no water contamination on the promotional pen | | | | an exception to the rule because they are clearly not |
| barrels themselves. Once cooled, the mouldings can | | | | moulded but extruded. In this case a metal former is |
| be ejected and this is achieved automatically when an | | | | used and the metal pen barrels are pushed off this |
| ejection pin is pushed into the mould from the | | | | former using a metal sleeve. As the meal is bashed |
| narrow end. It is very important that the pressure | | | | or extruded in the cold state there is no problem |
| used when doing this is minimal as the barrels, whilst | | | | with distortion as the barrel is ejected and |
| being solid, they are still warm and fairly pliable and | | | | consequently cylindrical shaped promotional pens are |
| consequently can distort easily under pressure. Making | | | | possible. All in all it is important to know that |
| the barrel taper throughout its length allows the | | | | manufacturing limitations often govern the shape and |
| barrel to be ejected from the mould more easily and | | | | design of promotional pens and sometimes this can |
| that is the reason promotional pen barrels are | | | | be the overriding factor when designing writing |
| tapered. | | | | instruments. |
| There are two exceptions to this however. Plastic | | | | |