Tuesday 26 January 2016

My Plastics Pioneers Series: LEGO®-founder Ole Kirk Christiansen & family

The idea of this blog post series is to present people who shaped and influenced our daily life with their capabilities in engineering, leadership, innovation, and in learning from their failures.

Let us start with a person behind a well-known toy: Ole Kirk Christiansen, the founder of LEGO® and a pioneer of the switch from wooden to plastic toys.
This post comprises two parts. The first part presents the LEGO® concepts and motivations, which can be useful to keep in mind for daily business, whereas the second part deals with the LEGO® technology from a more engineering point of view.
Part I: My favorite LEGO® concepts and views
Last year, I visited the home of LEGO® in Billund, Denmark. Here, the LEGO® funpark, R&D facilities and manufacturing are located.
I had the chance to have a look at the LEGO®’s idea house. Being inside this house allows you to make a time travel through the exciting history of LEGO®. Herein, several citations of the founder family can be found. They are placed all over the house together with example of toys from a specific decade. In this way, it is possible to get an idea of the views and concepts introduced by the founder family of LEGO®. Following, you can see some of these and how they can still be inspirational nowadays:

1) Godtfred’s LEGO® System of Play – approach:
LEGO® started by producing wooden toys. However, in 1954, Godtfred, one of the sons of Ole Kirk Christiansen, realized that little (plastic) bricks could have the potential to provide a system of playing, which would allow children to reversibly create their own world. 
Nowadays, 80% of the available bricks are standard types, whereas 20% are specialties. Standard bricks can cover over 200 different play sets. This has a huge beneficial influence in the mass production and designing of LEGO® bricks. Key message here: make your solution with system and simple (lean management approach).

2) Concept of the LEGO® founder family was based on 10 LEGO® main characteristics:

a. unlimited play possibilities
b. for girls, for boys
c. enthusiasm for all ages
d. play all year long
e. stimulating and harmonious play
f. endless hours of play
g. imagination, creativity, development
h. more LEGO, multiplied play value
i. always topical
j. safety and quality
 “The only toy that’s always right – because you made it” (LEGO®) - This is the result when creating products with those characteristics. It can also be a useful reminder when dealing with development of other polymer applications. You need to define boundary conditions and specifications for your product that your customer will start to love when using the product. Those boundary conditions should not only be taken into the industrial customer field, but they should also spread within your company and everybody needs to identify with them. Only in this way you will succeed with products and innovations.

3) “Our idea has been to create a toy that prepares the child for life-appealing to its imagination and developing the creative urge and joy of creation that is the driving force in every human being” Godtfred Kirk Christiansen, 1955

This thought states that your solution should add value in terms of creativity. And that we should never lose the creativity that we had as a child - “seeing it through a child’s eyes and mind” approach. When you ask a child: “Tell me 100 things you can do with a wooden stick”, she/he will possibly come up with 100 suggestions. As adults, we struggle already after the third suggestion. This needs to change. This kind of creativity we can stimulate by playing with LEGO®.

4) “LEGO stimulates creativity – it stimulates the ability to translate images of the mind to real expressions in the real world – in a way LEGO is a bridge between imagination and reality!” Godtfred Kirk Christiansen

This reflects also today’s possibilities in additive manufacturing and rapid prototyping, where images of our mind can become something touchable. Utilization of visualization technologies such as hologram projection allows designers and engineers to discuss items and ideas on a superior level. This consequently leads to a better understanding of the products and processes. When we understand those better we become more and more curios and want to know more.  This is one of the best driving forces for innovation!

Part II: LEGO® technology from a polymer engineering point of view:
The plastic
Polyolefins were initially applied for the injection moulding of the first LEGO® bricks as it can be seen in Figure 1, left.  Nevertheless, this simple design provided poor clutching ability between LEGO® bricks and, thus the construction of only simple toys. A new brick design was consequently needed. Designers eventually came up with a new brick geometry, the current one that we are all familiar with (Figure 1, right). This new geometry seemed promising, however, the polyolefine-based plastic at that time employed was not the right one. The low strength of this material resulted in the deformation of the bricks’ inner hollow cylinders purposefully designed to allow improved clutching. Several plastics were then checked and the winner was Acrylonitrile Butadiene Styrene (ABS). Since 1964, LEGO® elements are injection moulded in ABS.

Figure 1: Brick designs

The processing of the plastic
Figure 2: Windsor SH injection
moulding machine
The processing of the LEGO® plastic was mainly driven by Godfredt. Under the lead of Godfredt, the first injection moulding machine, a hand operating Windsor SH (Figure 2), was used to produce the first LEGO® plastic bricks. Back then, the machine operators estimated the cooling time by taking a puff of a cigar. The length of a puff was enough to cool down the brick in the mould.
Soon, engineers developed a new way of controlling the process of the moulded parts, the melt index control method also known as the LEGO®-process. For this, LEGO® established a quality system, which looks at the separation force between two bricks (clutching force). The quality testing system and the injection molding machine form a team being positioned next to each other. Once the clutching force is accessed, process parameters can be adjusted in order to attain the intended clutching force in the new moulded bricks.
Few parameters need to be set on the injection moulding machine and the production on one mould can be transferred to another machine, independently of material charge and machine.
What do you need for setting up the LEGO®-process on your machine?
  • Injection pressure
  • Injection time
  • Melt temperature
  • Melt index (estimated with the screw position in the injection moulding machine)
Important is that there is no separation between injection phase and the holding pressure phase. The injection time covers the injection and the holding pressure time. You just need to set the injection pressure. This results in the injection velocity. The flow resistance during the filling increases and the injection velocity decreases, because the set injection pressure will be not increased.
In this process, the melt index is defined as the time which the screw passes between two defined positions during injection. The melt index stays constant for achieving a constant quality. Is the index changing, then the injection pressure will be changed by the next cycle. In this way, an automatic quality control by adaptive changing of injection pressure can be implemented. Another advantage is that there is no switch over from the injection phase to the holding pressure phase. A disadvantage is that the injection pressure is as high as the holding pressure, which can lead to higher clamping forces. This can be a challenge when you want to make parts with thin walls where you want to have a fast injection (high injection pressures). In these cases, it is better to switch over short before complete filling to lower holding pressure.
Hope you liked the post! See you next time.

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1 comment:

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