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AUTOMATIC & SEMI-AUTOMATIC MODELS- knife sharpness and life tester (often known as the "CATRA TESTER")
Designed and Manufactured by CATRA

For an independent assessment of the machine see "BLADE" magazine March 2004

semi automatic edge testing machine

  Semi-Automatic model Automatic model
Test Stroke fixed 25mm or 40mm ( chosen at the time of ordering) adjustable 0 to 128 mm, Standard test 40mm
Test Cutting Speed fixed 50mm/s adjustable 0 to 150 mm/second, Standard test 50mm/s
Test Load 50N 25N and 50N( standard test)
Optional counter-balance not available 0 to 25N counter-balance weights for delicate blades
Max Depth of Cut 50mm 50 mm
Overall Vertical Capacity 105mm (including 50 mm of cut) making maximum blade width 100mm 105mm (including 50 mm of cut) making maximum blade width 100mm

700mm x430mm x1000mm

work bench mounted

1700mm x 1800 mm x 2000 mm

in own integral frame

Weight 40 kg 300 kg
Typical Test Time

Plain Edge Blade steel: 15 minutes (60 cutting strokes)

Serrated Edge Blade and ceramic knives: 30 minutes (200 cutting strokes)

Plain Edge Blade steel: 10 minutes (60 cutting strokes)

Serrated Edge Blade and ceramic knives: 20 minutes (200 cutting strokes)

Standard/ Norm International standard ISO 8442.5:2005 International standard ISO 8442.5:2005
Typical sharpness measurements from this machine

The Need for Sharpness measurement

CATRA has been involved in the testing of performance characteristics of blades for over 60 years. In particular the problems of evaluating the cutting ability have been studied using various manual and mechanical methods. This knowledge has enabled CATRA to design an automatic sharpness test machine that meets the requirements of consumers, manufacturers and standards organisations The need for such a cutting performance test is internationally agreed:

The International Cutting Test Standard BS EN ISO 8442-5:2005 Starting work in 1988 a group of specialists from various countries have developed a standard within the ISO Standards Committee for articles in contact with food. It specifies the detailed test method and sharpness specification for knives for the preparation of food. However, the test if ideally suited to other types of blades, including:

For more delicate blades such as razors, disposable surgical and medical blades CATRA recommends the Razor Edge Durability and Sharpness Tester

Testing of knife sharpening devices and systems

Not only can this system test knives, it can be used to test knife and blade sharpeners, by a clever system of testing and sharpening ( see below)

The system can also be used to measure the ease and abrasiveness of cutting various papers. By using standard blades and test cards made from the paper samples under investigation the machine will give very accurate performance figures, enabling paper processors to evaluate their cutting processes.

Testing Method

The principle of the test is simple. The blade is mounted in a position with the edge vertical and a pack of specially developed synthetic paper is lowered on to it. By oscillating the blade back and forth the blade cuts into the paper, the depth of the cut being the measurement of sharpness. The test media is loaded with 5% silica, which has a mild wearing effect on the blade edge. By repeating the back and forth motion, the further cuts are made, which wears the cutting edge. The measurement of cut depth at each subsequent stroke can then be plotted to produce a wear curve for each blade tested. The test produces two indications:

The test is designed for straight or nearly straight blades. However, specially modified machinery can be provided for circular or curved blades.

Computer Hardware/software

The Automatic test machine and control software is designed to operate on the industrial quality PC system built in to the equipment. The operating software interlinks with Microsoft Excel and Access to provide data analysis, reporting and database facilities, it has Windows 7,8 and 10 combatability.The software is optionally available with on screen information and reports in English, German, French. Spanish and Japanese.

The semi-auatomatic machine is is controlled a a programmable logic controller which manages all functions, measures the data and displays the resulting ICP and TCC and can output data with optional interface to Windows 10 computers.

Test Media

Specially formulated and quality controlled card with controlled Silica content of 5% supplied in: 10kg packs.......Thickness 0.31 mm > 0.02 mm.....Weight 200g 10g/m...Cut into Strips 10mm wide x 560 mm long . This is a complex test paper and is critical to the accuracy of the test system.

Machine Description

The CATRA Cutting Test Machine is generally as shown in the drawings below. The machine comprises of a rigid metal fabricated frame (Base & Cantilever) to which all major sub-assemblies are mounted. It is configured such that the blade to be tested is fixed, edge upwards, on a reciprocating table mounted onto the base of the machine whilst the test media (card) is applied, under load, onto the knife edge from the cantilever.

The blades to be tested can be easily clamped into the self-centering vice, which has a jaw design to compensate for blade thickness and taper in two directions. The centre line of any blade is therefore always the same datum; adjustable pillars support the blade and are used to set the attitude of the test portion of the cutting edge to as near level as possible. This design means that any length of blade can be accommodated, provided that the test portion is positioned over the vice jaws and is therefore supported.

The vice is mounted on a horizontal low friction slide which during the test is free to allow lateral float of the blade whilst cutting through the media, but returns to the fixed datum position for the beginning of each new cutting block. This slide is in turn mounted onto a horizontal table, which facilitates the longitudinal motion of the blade for cutting strokes. Drive to the table and therefore the blade is via a servo motor and lead screw arrangement, which allows precise positional and speed control over all or any part of the table's stroke. Therefore the test is carried out with a constant speed and motion envelope.

The test media (strips of card which are pneumatically clamped during cutting) is mounted in a holder with a capacity of 50 mm cutting thickness on a vertical low friction slide. Test load is applied vertically to the slide and therefore the media, by a calibrated weight. The method of lowering the media to the blade, together with the vice jaw design allows a full range of blade widths to be accommodated. Measurement of the amount of the card cut is achieved electronically. At the beginning of each new test and after each cut through the 'block' of media, the card is fed forward automatically by a pneumatic indexing system.

Operation of the machine is totally automatic (not on semi-automaticl version) except for the loading, setting up of the blade and replenishing the packs of cutting media. The machine functions are controlled by a microprocessor based unit, which switches electro-pneumatic devices and controls the motor under instruction of the resident program. This unit is in turn a slave to a host computer. The function of the PC is to provide the operator interface at the keyboard and to manage the test data, parameters, generate test reports and allow rapid comparison of current test data with the full database of previous reports. Test report are generated in Microsoft Excel and the data is stored in an Access database for easy future comparison and retrieval.

The flexibility of automatic machine design and software allows the user to 'develop' their own testing programmes (not manual version). Using the purpose written software specially developed 'in-house' at CATRA, the machine is capable of carrying out fully automatic cutting and wear tests on a blade with very little operator intervention. Results are stored onto disk ready for analysis using the supplied software or import to other proprietary data analysis software. The test allows the blade to cut through a maximum distance 50 mm of card whilst the controlling PC logs the depth of card cut per cycle and the number of cycles. These tests can be repeated any number of times and can then be displayed in tabular and graphical formats, as well as determining the results in any form required, including the initial cutting performance (ICP) and the edge retention properties (TCC) as specified in the ISO Standard.

The measurement of sharpness and cutting edge durability is not an absolute attribute (such as weight or length are) and as this system uses a practical approach of actually cutting, there are a considerable number of variables which can and do change. These are often outside of the accurate control of both CATRA and users of these machines, which means the level of absolute accuracy is relatively low in comparison with measuring a length with a micrometer for example. This system should therefore be regarded as a comparator for relative sharpness rather than for absolute measurements. If for example it is required to compare a knives it is better to test all samples on the same machine in the one location over a relatively short time period, this then increases the accuracy of the results.

Optionally, a single or 3 axis load measuring platform can be mounted below the blade vice to enable measurement of some or all cutting forces. This is useful as an instrument to aid in the development of knife edges for example in the minimising of cutting forces. The additional load measuring package includes a load cell, all cables, computer interfaces and integrated software.

The semi-automatic machine is a lower cost version, with no programmable functions, it has fixed stroke lengths, speed and test load. It can export the test data via an optional interface to Microsoft Excel spread sheet for analysis.

To test blade or knife a sharpeners or devices, the system can be operated in a different mode. By taking a particular standard knife blade and testing it on the machine up to a set number of cuts, then removing it from the machine, carrying out a resharpening operation using the sharpening unit under test and then returning the knife to the test machine, the performance of the sharpener can be gauged. It is normal for the above cycle to be repeated a number of times to evaluate the on going efficiency of the shapening or honing device. This then reveals a chart similar to the ones shown below. The technique can be used for measuring sharpening performance of the following devices and processes:-

Sharpening steels

Diamond and ceramic sharpening rods

Manually operated mechanical sharpeners with abrasive elements made of steel, carbide, ceramic aluminium oxide, silicon carbide or diamond

Electrically driven units with sharpening elements made of carbide, ceramic, aluminium oxide, silicon carbide, cubic boron nitride ( CBN or borazon) or diamond

Chemical, electro-chemical and other bulk sharpening processes

This test sytem is extremly sensitive when measuring the cutting edge "softening" effect which is created by overheating the edge by agressive dry power sharpening techniques and machines.

The following are some of the companies/organisations have the CATRA cutting test machine within their facilities
USA Dexter Russel, World Kitchen, Buck Knives, Spyderco, W R Case, Cutco/Alcas, Canada Cutlery, Leatherman, Bettcher , Stanley Tools, Fiskars Inc, Benchmade and 2 in un-named plants
Italy Fiskars Montana, Metallurgical materials laboratory Maniago
Germany FGW, J A Henckels, Hauni
Spain Madrid University, Arcos
Portugal CATIM, ICEL
Switzerland Victrinox/Wenger
UK Amefa ( Richardson Sheffield), Stanley Tools
Japan Master Cutlery (Global Knives), Yoshikin
China Great Star Tools, Wiko Cutlery, SGS , Sam & Lam, Blue Print, Shanghai Owa
Taiwan un-named company
India un-named company
Sweden Mora, Munkfors
France Adiamas

and of course CATRA, we have 2, which have tested knives for over 2000 companies Worldwide

Automatic and semi-automatic machines available for sale

Semi-Automatic machines available for short term rental for a short term project.

Or CATRA offers full independent and confidential testing services based on these machines.

Visitors to Sheffield are most welcome to come to CATRA to see these fascinating machines.



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CATRA, Henry Street, Sheffield S3 7EQ, Great Britain Fax: +44 (0)114 272 2151 Tel: +44 (0)114 276 9736