Cleverly Solve Construction Crises

2023 Author : Hannah Pearcy | [email protected] . Last modified: 2023-11-26 11:39

Construction crises, triggered, for example, by construction errors or also by unforeseen situations, are a well-known bogeyman in mechanical and plant engineering . The alternate dependency on suppliers and operators of machines and systems usually triggers extraordinary efforts on the part of suppliers to remedy the defects. In contrast to, for example, recall campaigns in the automotive industry, these events hardly reach the public

Within the special branches and in the companies there is a lively exchange between the experts about construction errors and their correction. The subject [1] [2] is also dealt with in the literature. To the consolation of practitioners, it is written that crises can never be completely avoided . This is demonstrated by some impressive examples.

Based on experience gained from the author's professional activity, this article uses three practical examples to show how crises were managed . The examples have been removed from their more complex context. In retrospect, the solutions seem almost trivial.

• Everything described comes from relatively small, specialized companies in mechanical and plant engineering.
• Because of the time interval, the descriptions of the events are rather blurred. Nevertheless, all examples contain a timelessly transferable core.
• The summary of the examples does not make any scientific claims and offers no “magic recipes”.

Overcoming departmental boundaries

One design of an industrial furnace was equipped with various hydraulically operated flaps. In order to increase the throughput of the batch-operated unit, a new order was made to change the sequence of movement of the flaps during filling and emptying. After placing the order, the hydraulic specialist ordered the hydraulic system in the same way as for previous projects. The designer gave the workshop drawings of the flaps, copied from preliminary projects, to production. It turned out that the new sequence of movements resulted in increased, uncovered, oil consumption . Solutions such as the installation of larger hydraulic pumps were ruled out due to time and cost reasons.

The concept of the flap and its drive, which has remained unchanged for many projects, has now been examined more closely. Figure 1 shows it: The damper blade seals the furnace space and holds back the product. After pressure equalization, the valve with the hydraulic cylinder is opened. The result: In the "inherited" design, the hydraulic cylinder was attached unfavorably . The ring surface of the piston worked in tension to press the damper blade. For easy opening, however, the piston surface pushed and used up oil unnecessarily.

After this discovery, the solution was quickly found: by replacing the valve, the oil consumption for this movement could be halved . So there was enough oil available for the other simultaneous movements. The successful way out of the dilemma was that the specialists had found each other, uncovered a hidden feature and used it across disciplines.

Recognize and use hidden reserves

The second example is about a new circular saw machine. Figure 2 shows how this machine could not only trim the so-called "side boards" in a sawmill, but also perform the "re-cutting" flexibly. A customer of the machine factory showed interest in the new product, but wished to use more saw blades with a higher cutting height when re-cutting. A check showed that the drive motors of the saw shafts were too weak for this . A supposedly safe order was about to burst.

For reasons of space, the installation of larger motors was only possible with considerable changes. So you delved into the documentation of electric motors. The motors were designed for nominal load in continuous operation. Due to the alternation of trimming and trimming and the idle times for loading the timbers, the motors only had to deliver maximum torque in about a quarter of the time, and in three quarters of the time they turned almost at idle.

This “hidden reserve”, which was unknown during development, enabled the motors of the same size to demand the desired approx. A quarter of additional power without thermally overloading them. This and other orders could be processed. The crisis, which already occurred in the acquisition phase, was resolved by taking a holistic view of the system and a little luck in finding the "hidden reserve".

Construction methods

Heuristic traps in construction

Take damage seriously

A new machine for automatically trimming boards has been developed. Thanks to the new type of opto-electronic measuring technology at that time, a high utilization of the raw wood could be achieved. Prototypes went into operation successfully. Everything new in the development worked well. However, during operation it became apparent that the incremental linear encoders, which reported the position of the movable saw blades, could not withstand the dusty and vibrating operation . This type of encoder, at that time the market for such things was still small, was the most robust that was available. The supplier's response to the damage was a polite shrug.

The crisis for the machine factory was great because the series for the subsequent orders placed was produced. Luckily, a designer took the initiative and designed a rack-and-pinion gear to which a tried-and-tested encoder was attached (Fig. 3). Thanks to early consultation with the manufacturing department, the design was quickly implemented and after a few weeks the insidious weak point was eliminated. The obvious additional effort was accepted. The crisis was eliminated by trying not to save the unsuitable measuring device anymore, but to replace it in such a way that it was "inherently" reliable. The question in the room was not "Make or buy?" But "Make or die!"

review

Construction milestones

Conclusion and summary

The examples show that in times of crisis, solutions can be found within a reasonable time that have been progressive beyond the day. Of course, this does not always have to be possible. In contrast to day-to-day business, factors that help to find and implement solutions become more effective in crises:

• The problem is not hidden in the technical documentation, but is evident in the operation of the realized technical product.
• The responsible designer is forced to switch from "normal operation" to "rational operation", as stated in [1].
• The thresholds of arrogance like "Not invented here" and "Throw over the wall" [1] have to be lowered.
• Despite the tight deadlines, cost-saving solutions were found in Examples 1 and 2. The higher expenses for the travel agents in the third case were more than made up for by the lack of complaint costs.
• At first glance, the possible solutions in the crisis seem to be severely limited. The examples, on the other hand, show that "hidden reserves" hidden in crises can be uncovered, which surprisingly expand the "scope for solutions" [1].

Finally, it should be noted that the solutions developed in the crises represented an increase in explicit and implicit knowledge for the companies in all three practical examples [3]. Since crises are always linked to a “story”, they tend to remain anchored in the collective memory of the company.

literature

[1] K. Ehrlenspiel, H. Meerkamm; Integrated product development; 6th revised and expanded edition 2017

[2] U. Lindemann; Methodical development of technical products; 3rd revised edition 2009

[3] VDI guideline 5610 part 1; Knowledge management in engineering, basics, concepts, procedure.

Seminar tip

The seminar The control of the design area conveys how key figures can help as a control instrument, what the most important parameters are and how a suitable key figure system is implemented - using a practical example.

* Andreas Loebner, freelance author, Bern