Surface finishing, grinding, deburring, polishing is typically considered as labor intensive work stage with low cost tools – and as such not worth of automating. In many cases this kind of superficial thinking leads to false conclusions and ultimately to the loss of competitive edge in business.

1. Making the case for robotized surface finishing
By Olli-Pekka Holamo
https://www.linkedin.com/in/ollipekkaholamo
Surface finishing, grinding, deburring, polishing is typically considered as labor
intensive work stage with low cost tools – and as such not worth of automating. In
many cases this kind of superficial thinking leads to false conclusions and ultimately
to the loss of competitive edge in business.
Introduction
In this article the topic will be discussed
from multiple angles including some
business-critical views. Investment to
production automation should always be
considered as a strategic move because
it will not only bring new equipment but
changes the way of working on shop
floor. That said, it should be obvious that
comparing current manual way of working
to robotized concept is not that straight
forwards as many business managers
would like to think.
Old fashioned ROI approach:
Current situation: Company produces
metal products and there is a need to
perform deburring after machining and
grinding after welding operations. In worst
case there is no tracking of used hours
for this work so there is actually no
knowledge about how much time it takes
or how much it costs for the company.
One tip: check how much money is
annually spend on consumables –
grinding discs/belts etc. There is a
relation to actual working time. Next step
is to try to figure out what the fully
burdened* manual grinding hour really
costs for the company.
*workplace area, supervision, taxes, other
overheads, workplace tools (manual,
overhead cranes etc.), quality costs etc. See
picture below:
Source: https://ec.europa.eu/eurostat
Following chart includes some, but not all, of
the labor costs in European countries.
Source: https://ec.europa.eu/eurostat

2. Example calculation:
Labor cost (Finland): 33 Euro/hour.
technically available annual working
hours for a worker: 1732 h.
Hence, labor cost per year: 57156 Euro.
Now the actual available number of
working hours is smaller than technically
available, because we need to deduct
sick leaves, time for training, union work,
family leave and other absence. These
deductions are, according to statistics,
about 20 % from the technically available
time.
Actual available annual productive
working hours/worker:1386 h
Hence, actual cost for productive working
hour: 41 Euro/hour
Even if the company lacks accurate
surface finishing hour statistics, we can
look at the investment form other side, by
looking at the capacity which is provided
by the robot investment.
Cost for a robotized solution is approx.
something like 300 000…500 000 Euro
Available working hours for the robot can
be calculated for example as follows.
Number of annual available working days:
251 days/year, hours per shift: 8h,
numbers of shifts per day: 2.
Annual available robot cycle hours: 4016
hours/year.
Investment payback
period**:7273…12121 hours = 1,8...3
years
**calculated in an old-fashioned way as robot
replaces the manual work
If manufacturing operations can be run in
3-shifts, the payback period is reduced to
1,2…2 years.
When comparing robotized work with
manual labor it must be noted that
surface finishing is not that attractive work
and thus it might not even be possible to
get enough manual workers to do it. Lack
of work force results in longer lead times
and loss of business opportunities.
Conclusion
A payback period less than three years is
typically very interesting and therefore,
even by looking only this traditional
method, a closer look should be taken to
find out if there are enough surface
finishing hours used in company to justify
the investment.
The other, but very significant,
factors to be considered
Above mentioned was just the tip of the
iceberg. There are lot of others and
usually more significant reasons to
robotize grinding etc. processes, than just
the straightforward payback time
calculation indicates.
Automation takes whole production to
another level. For example, RIA lists
many important aspects on their web
page (https://www.robotics.org)
• Product quality and consistency
• Product and process waste
• Traceability
• Safety
Even if we would not be able to increase
the efficiency of the material removal
process, robotized production tends to
increase actual overall tool on contact
time in grinding due to shorter air
movement times and lack of breaks. In
other words, higher yield per hour with

3. less waste and consistent quality is
achieved.
Considering surface finishing related
operations, health and safety aspects
are one of the most critical investment
drivers for any responsible company.
Almost 25% from manually held electrical
tool related accidents occur when working
with angle grinder***. Heavy products,
fast spinning discs, heavy tools,
unergonomic working positions and
orientations lead to high risk environment
for the worker. Humans get tired and
sloppy, and even if the accidents are
avoided the quality gets naturally lower
over extended working hours.
Exposure to constant vibrations from
handheld tools cause hand-arm vibration
syndrome, a.k.a. “vibration white finger”.
As a counter measure, local laws can set
limits on exposure times for vibrating
machinery for workers.
*** Source: Deutsche Gesetzliche
Unfallversicherung e.V. (DGUV): Statistik
Arbeitsunfallgeschehen 2017,p.64.
In long term, the exposure for any kind of
fine dust is extremely harmful. Proper
personal protection must always be used.
But in real life the workers too often
remove the respiratory protection right
after the grinding disc is detached from
workpiece, its only human – and thus get
exposed to dust, which is still hanging in
the air. Dust irritates nose, throat and
eyes and finally gets in the lungs and
small particles less than 2,5 micrometers
in aerodynamic diameter can get even
into the bloodstream. This is unhealthy
and for example World Health
Organization (WHO) has recognized
chrome as carcinogen. Chronic exposure
to Cr increases the risk of lung, nasal,
and sinus cancer. Molybdenum exposure
in turn can cause weakness, fatigue,
muscle and joint aching and anemia.
Inhaling simple iron dust from low alloy
steels cause welder’s disease, which is a
commonly known health issue, without
cure, among steel workers.
And there is yet another potential danger
with the dust – it can be explosive. This is
specially the case with titanium and
magnesium. Working with such
substances requires increased safety
measures, like using cutting fluids with
proper air conditioning. But using cutting
fluids in manual work presents a dilemma
and is not often feasible choice for such
kind of operation at all.
Noise levels cannot be neglected either,
in heavy grinding the 85dB limit is easily
continuously exceeded. Health
consequences of regular exposure to
such high noise levels cause hearing
impairment, tinnitus and sleep
disturbance and stress among other
symptoms. Increased stress levels in turn
contribute to higher accident rates.
Amount of sick leaves varies a lot
depending on work, but 4…6 % from
working hours is typical. In certain metal
industry tasks, like in grinding work, it
could even be higher.
Conclusion
Eliminating health and safety related
risks, cutting sick leave related costs and
getting lost capacity to productive work
should present self-evident motivation to
study feasibility of robotized surface
finishing in any company. Robots are
unaffected by health symptoms and the
dust. Noise level control can be arranged
effectively without putting humans at risk.