159 / 164
157
M
ay
/J
une
2007
The current costs of disposing of the solid saw waste are €0.4/kg.
Thus, to dispose of the 6,500kg of waste costs €2,600 per year.
Waste from a shear cut is solid and can be sold for €0.1/kg.
Therefore by using this technology, instead of the assumed costs of
waste removal, a profit of €1,950/year can be achieved.
The overall benefit to the producer is €4,560 per year.
D) Increase in production as a result of using shear cutoff
Additional savings result from the increased production as shown
by the following two examples. Let us assume an annual production
of 26,000t/year.
Analysis of production data shows an increase in production when
using shear cutoff by 43 hours, as a result of shorter necessary
stoppages for cutting tool maintenance.
Increase of profit as a result of less stoppages per year:
42 x 60 = (2,580min) x (60m/min) x (2.8kg/bm) = 154,800kg/year.
Assuming a profit of €0.06/kg, increase of profit per year is €10,000.
It can therefore be assumed, and actual production experience
confirms this, that a forming line producing a profile 60 x 40 x 3mm
will increase productivity by 20-30 per cent (assuming sufficient HF
welder capacity) when the mill speed increases (graph 2).
Using the assumed production of 26,000t/year the increase in speed
will bring approximately 6,500t more production. At the above profit
of €0.06/kg, using shear cutoff instead of a cold saw, will result in
extra profit of €390,000 per year.
If this theoretical profit is reduced by a coefficient of 0.6 to
accommodate a realistic assortment of other profiles, it results
in an extra profit of €235,000.
Now it is clear, that from the point of view of A), its increase in profit
is almost negligible when compared with B).
From the economical point of view, dividing by shear is definitely
more profitable, in this case by €235,000/year.
Therefore, calculations can be made regarding the payback period
on investment in case of installing a flying shear cutoff machine
Alda 76 X 3 – 100.
The total saving per year is:
A + B + C + D = 34,000 + 21,000 + 4,500 + 235,000 = €294,500/
year.
Investment in buying the machine:
€150,000
Investment in buying the necessary tools:
€15,000
Installation and the original set up:
€8,000
Total costs :
€173,000
Yearly savings:
€294,500
Thus the return is 173,000: 294,000 = 0.6 year
The return on investment based on the above analysis is just 0.6
a year (8 months), without even evaluating the additional positive
effects on hygiene of work, ecology and internal costs.
Please note: All the above data has been compiled from information
offered by companies Attl a spol sro, JAKL Karvina as, Steel Profil
sro and Ocelprofil sro.
Recommendations for both dividing
technologies for tube/profiles by flying cutoff
After twelve years of experience in this field, the findings can be
used to recommend an optimum type of dividing tubes and profiles
with respect to the types of profiles and tubes, the maximum
possible capacity of a production mill and the quality of the cut face
required. We have divided the choice of machines produced by the
Attl a spol sro into five groups as follows:
Flying cold saw Alda s 38 x 2.5 -140
Parameters
Values
Units
Tube diameter max/min
38/10
mm
Square profile max
30 x 30
mm
Rectangle profile max
50 x 10
mm
Wall thickness max/min
2.5 ÷ 0.8
mm
Material
S 185; S 235
JRH; S 235 JR;
1.4301; 1.4571
Mill speed max
140 (160)
m/min
Rotary saw diameter
400
mm
Number of cutting cycles for L= 6m
22
1/ min
Life of rotary blade between sharpening (est)
100 ÷ 160
t
Power input
120
kW
Comments: This is a proven type of flying cold saw with extra
high rigidity of the saw unit and proportional control of feed motion
by hydraulic cylinder. Using this saw for cutting the above small
diameters does not offer substantial economic benefits.
›
Figure 3
:
Flying saw cutoff Alda s 76x3.4-100, with AUT 7000 bundling
machine shown in the background
Graph 2