Evaluation of package appearance and test methods: a case
study at Tetra Pak Research and Development AB

Abstract: This degree project was carried out at Tetra Pak Research & Development AB
in Lund, a unit within Tetra Pak with 250 employees. Tetra Pak develops,
produces and markets complete processing, packaging and distribution
systems within the food sector. Tetra Pak Research & Development AB is a
unit that supports all business areas within Tetra Pak. In 2003, the unit
started the development of a new package with specific characteristics. The
package is a 1000 ml aseptic package, which packs milk for long shelf life.
It is called PLDP – Package for Liquid Dairy Product.

The main purpose of this study is to evaluate different measuring
instruments and test methods concerning appearance aspects of the PLDP at
Tetra Pak Research & Development AB. Furthermore, the purpose is to give
recommendations on what actions need to be taken to work efficiently with
the area of package appearance.

To attain the purpose a case study with values, methodologies and tools
from the Total Quality Management system was conducted. A range of
operations was made to gain an understanding of the PLDP project and its
connections to appearance aspects of the package. For instance, a careful
mapping of the current way of working with appearance at Tetra Pak Research
& Development AB was made. Moreover, a suggestion of an improved partition
of the appearance of PLDP was made. This was the starting-point for the
identification and prioritisation of practicable features for this study to
continue with. Also it facilitated the evaluation regarding measuring
instruments and test methods, by viewing the partition in a new and
organised way. The features evaluated in this study are Bulging and Visual
Damages. In addition, several interviews with strategically selected
employees within Tetra Pak were conducted. These interviews formed a basis
for defining the conception of Package Appearance, which the area is
called. The definition of Package Appearance was crucial to help the author
to keep the red thread throughout the entire study.

The evaluation of Bulging and Visual Damages was made in different ways.
First, available instruments to measure Bulging of the PLDP were listed.
Two instruments were decided to go through a further investigation by means
of a Measurement System Analysis (Gauge R&R). Such an analysis determines
whether variation comes from the packages being measured, differences in
operator measurements or the measuring instrument. The results show that a
higher precision and a faster measuring procedure, almost without any
influence of different operators can be obtained with a laser instrument.
The second instrument to be analysed in a Measurement System Analysis was a
calliper. According to Signal-to-Noise Ratio (SNR), this instrument was not
a proper measuring instrument for this purpose. However, a laser instrument
and a calliper are associated with different costs and these need to be
taken into account in an investment situation.

The second feature, Visual Damages, was investigated by first determining
which sub features to include in this feature. These sub features formed
the input in the conduction of a test method consisting of photo references
to compare with the actual defects of the packages. To reduce
misconceptions when testing different features of a package, the author
suggests working in accordance with such a method which puts references
together of what is right and what is wrong among machine operators,
laboratory personnel and project leader.