Sawing machines and systems builder Kasto said that cutting to length is often regarded as a preliminary operation in the life cycle of a product and not a value-added process.

 

There is a tendency for manufacturers and stockholders to skimp on the purchase of a saw.

 

Kasto said that all expenditure has been taken into account, so the questions every saw owner should ask are as follows.

 

* What is the total cost per cut.

 

* Or: how much does it cost to cut an area of one square metre.

 

Kasto told manufacturingtalk.com that it is not enough to consider only the price of a machine.

 

The total cost of ownership (TCO) has to be taken into account, including consumables, operator wages and service over the lifetime of the machine, in addition to the capital cost.

 

Only then can proposals from different sawing machine vendors be evaluated properly.

 

Improved cutting performance, increased output, better quality of cut and a greater degree of automation have led to significant improvements in bandsaw technology, utilisation and efficiency in recent years.

 

This has happened in parallel with the development and increasing use of carbide rather than bimetal bandsaw blades.

 

In comparing the cutting performance of a traditional bandsaw with that of a KASTOtec AC4, designed for cutting with tungsten carbide tipped blades.

 

The material was 300mm diameter 42CrMO4V alloy steel.

 

Kasto's data shows that the performance of its machine is 2.5 times higher, with cycle times reduced by 36% and the total processing time of the sample order reduced from approximately 58h to 20h (Full table is available from Kasto).

 

Kasto maintained that such performance can only be achieved with a stronger, more powerful and robust bandsaw, with improved vibration damping characteristics and better dynamics regarding cutting and idle times.

 

This in turn dictates a higher price compared with traditional bandsaws.

 

The question whether or not the more expensive machine is the more cost-effective is one that cannot be decided based on the capital investment alone.

 

* TCO approach includes all operational costs - in addition to the price of the bandsaw, a TCO analysis must include all operational costs over the lifetime of the machine.

 

Since some costs for floor space, energy, and swarf disposal are comparable for all machines, for the sake of clarity they will be disregarded in the following calculations.

 

Thus the only costs to be considered will be as follows.

 

* Machine utilisation requirements, investment, depreciation and interest charges.

 

* Tool costs, idle times.

 

* Factory supplies - coolant.

 

* Service costs and maintenance.

 

* Labour costs.

 

The normal depreciation period for a KASTOtec AC4 is 10 years, so this was used to calculate interest payments which were added to the capital cost of the bandsaws.

 

A carbide bandsaw blade costs EUR 280 and has in this calculation a lifetime of one week when operated over a single shift.

 

Since production saws, especially machines with automatic material feed, are often cutting 'around the clock', three bandsaw blades are necessary per week.

 

Over the course of a year with 220 working days in three-shift operation, tool costs are EUR 36,960.

 

Factory supplies play only a secondary role: coolant is lost due to evaporation, sticking to chips, vapourising or vacuuming and about 35 litres per week are needed, which costs EUR 620/year when using coolant concentrate mixed in a 1:10 ratio.

 

Machine availability and maintenance are of great importance for every company.

 

Particularly during production cutting or in steel distribution, maintenance contracts are recommended, which guarantee quick exchange of wear parts and spares.

 

In this example, service costs were averaged over several hundred machines and an typical travel time for the engineer was taken.

 

Over a period of 10 years, service and spares cost approximately EUR 33,500.

 

Based on the machine investment, service costs represent just over 4%, about double the amount suggested by the VDMA (the German Association for Machine and Plant Manufacturers).

 

The reasons for the disparity may be a combination of harsh operating conditions, frequent personnel changes and poorly trained operators.

 

Personnel costs, in spite of higher automation, should not be underestimated as a cost factor.

 

This example is based on multiple machine operation.

 

Assuming that 20% of the personnel costs are for setting-up, cut piece removal from and order entries relating to any given saw, the costs amount to an annual total of EUR 26,400/saw, based on 220 working days and three-shift operation.

 

Kasto's data shows that over the first 10 years of a KASTOtec AC4 bandsaw's life, machine investment represents only 15% of the total costs, compared with a massive 48% for tooling costs and 32% for labour.

 

Other cost elements are coolant (1%) and service (4%).

 

In respect of the latter, speed and quality of service are important, as if spares are missing or not fitted correctly, the result is machine downtime and lost production.

 

* Total costs: KASTOtec AC4 compared with a conventional machine - comparing all lifetime costs of the KASTOtec AC4 with those of a conventional bandsaw, Kasto data showed that a traditional machine requires around 50% less investment and 43% less in high-speed steel bandsaw blades due to the machine's shorter operating life.

 

So taking into account just these two factors, the machine is around 30% cheaper.

 

Nevertheless, investment in a more expensive, high performance machine is justified from technological and economic standpoints.

 

First, a carbide bandsaw can cut tough materials up to a tensile strength of Rm =2000 N/mm2, which cannot be sawn with traditional machines or blades.

 

Second, the carbide saw has a more efficient cutting performance, resulting in shorter cycle times.

 

Third, longer band life requires less frequent band changes and therefore reduces labour costs and machine downtime.

 

A productivity comparison shows that over a period of 10 years, the carbide machine cuts 2.6 times more material than a traditional machine (Kasto data).

 

If one converts the total cut surface to cost/m2, Kasto's data showed that the figure for the KASTOtec AC4 is 48% lower than for the conventional machine, or nearly half.

From: Manufacturing talk.com