Ergonomics as Significant Factor of Sustainable Production - Technology Management for Sustainable Production and Logistics - page 193

Table 2 Human failures in production processes classification (own source)
Operator decision Real process/product status

Acceptable product

Not acceptable product

Acceptable product OK Second type of failure

First type of failure OK

Not acceptable product

From operational effectiveness point of view, work in three shifts working sys-
tem is connected with risk of two types of human failures (Table. 2 ). First type of
failure are failures that are results of improper sub products or ready goods clas-
sification. This type of failure influence on quality costs increase of manufactured
products. Second type of failures are also called missing of overlooked failures. In
case of missed failures there is a risk of sending out defective product to customer.
Causes of failures presented in Table 2 could be many and different. Beginning
from aspects of work place ergonomics, work ergonomics, to psychological, phys-
ical, behavioral, sociological or social factors. In so far as part of failures can be
corrected, formed, or improved, rhythm of activities strictly related to human bio-
logical abilities and limitations is not changeable.
Special case study presented by authors is visual inspection in production pro-
cess. It is undoubtedly one of production steps with human playing the main role.
Visual inspection effectiveness depends mostly on human abilities/possibilities,
predispositions and working conditions as well. Special case is alternative, organo-
leptic, visual inspection, still the cheapest control comparing to different control
types, nondestructive but with a big risk of human error appearance as described
above.
For proper analysis of ergonomic work places aspect as also work methods
in sustainable production processes, their influence on single operators should
be examined. Analysis should not be influenced by outcome for group of opera-
tors. Average effectiveness for group of operators indicates discrepancy between
the strongest (the most effective) and the weakest (the least effective) operators
in group. Group means team of employees working in particular area, production
nest, or work place, with similar level of abilities and status of training.
Analysis of three shifts working system influence on visual inspection effec-
tiveness was performed in manufacturing company, producing electronics subas-
semblies for automotive industry. Researches carried out during 33 weeks. Data
was collected from three production shifts (morning-I—6 a.m. to 2 p.m., after-
noon-II—2-10 p.m., night-III—10 p.m. to 6 a.m. next day) about missing failures
made by fours sequentially placed visual inspection. Visual inspection effective-
ness analyzed with FPY 1 index. Bigger index then bigger visual inspection figure.
Data analysis of visual inspection effectiveness collected for group of operators
shows that effectiveness fluctuation is not visible on different production shifts but
rather between groups of operators (inspection stations) (Figs 1 and 2 ). Regardless

1 First Pass Yield (FPY) [0-100 %] is number of found nonconformance to total number of non-
conformance available to find.