Comparison between Blister Machine at Home and Abroad

We started the research and development of Blister Packing Machine in 1985, and introduced the first sample in 1989. Continuous improvement made our product accepted by lots of customer in China, and also some customers in Southeast Asia. We are delighted for ourselves for contributing to the popularization of Blister Packing Machine for drugs.
We will briefly present the functions and characteristics of this machine and compare it to other similar packing machines:

I. Comparison between Roller-type and Plate-type Moulds

  1. Functions and characteristics of roller-type machine:

(1) For roller-type mould, circulating water cooling is needed when the PVC sheet closely placed against the mould enters the heating section as the roller rotates to enable heating in limited die orifices (the rest heat is removed as the mould cools). Plus, the vacuum forming is the only option here. Therefore, the forming temperature is relatively high (about 170 °C, approximately the melting point of PVC, which is 180 °C, at which the chloride would start to decompose), resulting in thin blister bottom, and uneven wall thickness. For PVC sheet with scratch, broken blister is a probability due to concentrated stress. Therefore, vacuum forming requires good quality in PVC sheet. (Vacuum forming refers to by evacuating the air inside the mould, (generally 1.33×10-2-1.33×10-5Pa in actual situation, for absolute vacuum is impossible in practical application), the pressure difference between the air and mould would generate pressure, usually called negative pressure, with maximum value of standard atmospheric pressure).

(2) For drug of abnormal shapes, great difficulty in mould processing makes it hard to apply the process.

(3) Synchronization is the biggest merit of roller-type machine.

  1. Functions and characteristics of our plate-type Blister Packing Machine:

(1) Our machines adopts plate-type mould, in which heated PVC sheet is conveyed to the forming mould for positive pressure forming. Because of high compressed air pressure (0.3 MPa generally), low temperature (about 100 °C, the PVC sheet starts to soften at 90 °C), large forming and heating area, and the fact that the blister is not only drawn from the rigid PVC sheet at the mould orifice but also around it, therefore, the wall thickness is even and of good strength, which demands less for the quality of rigid PVC sheet.

(2) Convenient mould processing, and suitable for the package of various drugs of abnormal shapes.

  1. The difficulty comes from the synchronization between the forming mould and heat sealing mould, i.e. the formed blister cannot be exactly dropped into the orifice of heat sealing mould.

II. Comparison with Foreign Machines

  1. German machine has the technology of using close shift counter for the forming mould to trace the movement of PVC sheet, but this device is complicated and costs a lot.
  2. FA3 machine from Italy FAX adopts synchronized motor to drive the roller, and photoelectric feedback control to eliminate error, but with little effect.
  3. Our DGB-250 multi-function roller-type automatic Blister Packing Machine assimilates the merits of smooth process and clear production procedures in FA3 machine, with redesigned synchronization mechanism of mechanical transmission for intermittent action, which makes the driving roller would have four intermittent actions as it rotates every circle. This movement structure is driven by the main motor the same as the other movement structures. As a result, the equal error is limited in one circle and accumulated error is removed which solves the synchronization problem of the machine (national patent No. 90203244.5).

III. Solution to Printing Ink Volatilization Issue during Printing
Topping printing (resin plate generally) is the popular choice of German, Italy and domestic Blister Packing Machine. The disadvantages for this technology are rough line, deckle edge, and unavoidable stains in blank area, which make promotion a hard job for product appearance.
As to photoengraving intaglio printing, it brings fine lines, and clear picture, and suits almost all characters, trademarks of varied shape. Required by the process, the printing ink should be diluted, which means the use of volatile chemical diluents, like dimethylbenzene and consequently pollution to the surrounding environment. Foreign institutions have ever invested huge fund into developing nontoxic printing ink, but received little result. In addition, the manufacturing cost is expensive, about 70,000 yuan/ton.
We independently designed and manufactured “sealed intaglio printing device”, which fully takes advantage of the intaglio printing, and also avoid the environment pollution issue caused by diluents volatilization through using intaglio ink for ordinary plastic film (around 10,000 yuan/ton) (national patent No. 91228830.2).

Yang Yijun, Jornen Machinery Co., Ltd.
(Published at the Pharmaceutical Machinery News on May 30, 1992)