AUTOMATIC & SEMI-AUTOMATIC MODELS – knife sharpness and life tester (often known as the “CATRA TESTER”) Designed and Manufactured by CATRA
- Measures the sharpness and edge life (durability) of a large range of blades & knives for quality control, research & development and competitor product evaluation
- Quickly and accurately measures important cutting performance data
- Fully automatic model allows operator to multi-task
- Automatic model is completely programmable to allow operation to the standard or users’ own specification
- 41 units in use throughout the world
- The only proprietary cutting test machine on the market conforming fully to the International Cutting Test Standard BS EN ISO 8442-5: 2005
- Fast low labour cost automatic version of the sharpness tester is ideal for large sample sizes and extensive development projects
- Lower capital cost semi-automatic test machine is ideal for smaller research projects and low volume quality control use
For an independent assessment of the machine see “BLADE” magazine March 2004
Standard/ NormInternational standard ISO 8442.5:2005International standard ISO 8442.5:2005
|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|
|Size||700mm x430mm x1000mm
work bench mounted
|1700mm x 1800 mm x 2000 mm
in own integral frame
|Weight||40 kg||300 kg|
|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:
- to monitor the consistency of quality of cutting performance against the norm of manufacturing to be sure that the knives are within the standard values agreed upon
- to be used as a development tool to enable research into the optimum steel, heat treatment, surface coating, edge geometry and finishing operations to suit the application
- to compare objectively various knife blades and determine which one is superior to another
- The machine system answers the questions ” How sharp is it?” and ” How long will the sharpness last?“
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 is also ideally suited to other types of blades, including:
- Kitchen, Professional and Trade Knives
- Hunting, Folding, Pocket and Sporting Knives
- Machine and Industrial Knives and Blades
- Band blades and knives
- Agricultural Knives and cutters
- Handicraft blades, Utility blade, DIY, Craft, Box Cutters and Tool Knives
- Surgical Blades, Medical Cutting Edges
- Wood chisels and Plane blades
- For Hooked utility and other very short curved edge blades a special option is available using an alternative cutting system
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.
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 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:
- ICP (Initial Cutting Performance) representing the cutting ability (sharpness) of the blade as supplied
- TCC (Total Card Cut), sometimes refered to as CER, cutting edge retention, which represents the life of the blade by giving a measure of its total cutting ability
The test is designed for straight or nearly straight blades. However, specially modified machinery can be provided for circular or curved blades.
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 and is compatible with Windows 7, 8 and 10. The software is optionally available with on screen information and reports in English, German, French. Spanish and Japanese.
The Semi-automatic Machine is controlled a programmable logic controller which manages all functions, measures the data and displays the resulting ICP and TCC. Data output can be captured with an optional interface to Windows 10 computers.
Specially formulated and quality controlled card with Silica content of 5% supplied in: 10kg packs…….Thickness 0.31 mm >± 0.02 mm…..Weight 200g ± 10g/m²…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.
The general arrangement of the CATRA Cutting Test Machine is 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 are clamped into a self-centering vice where the jaw design compensates for blade thickness and taper in two directions. Hence, the centre line of any blade is always to 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. The design also means that any length of blade can be accommodated.
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, abd 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. This allows precise positional and speed control over all or any part of the table’s stroke. Therefore the test is carried out within a defined 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. The 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 reports 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 displayed in tabular and graphical formats, as well as presenting the results in any format 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, as there are a considerable number of variables in the analysis. These variables 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 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 a blade or knife sharpener, 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 sharpening or honing device.
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, aluminum oxide, silicon carbide, cubic boron nitride ( CBN or borazon) or diamond
- Chemical, electro-chemical and other bulk sharpening processes
This test system is extremely 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|
|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|
and of course CATRA, we have 2, which have tested knives for over 2000 companies Worldwide
Automatic and semi-automatic machines available for sale
Visitors to Sheffield are most welcome to come to CATRA to see these fascinating machines.