Research and Development Special Purpose Machines Cutlery and Consultancy Services Quality Testing ______Allied Laboratories and Registered Office: Henry Street, Sheffield S3 7EQ Director of Research Trades United Kingdom R C Hamby C Eng M I Prod E
Tel: 0114 276 9736 Research Fax: 0114 272 2151 E-mail: [email protected] Secretary Web: http://www.catra.org Mrs T A Couldwell MIQPS Association ______
Our ref: GEG/965905
25 January 2008
Forever Company Ltd 1-3-19 Sakae-Cho Kwaguchi-Schi Saitama Ken Japan 332-0017
For the attention of: Akira Hirai
Sheet 1 of 6
Report Number: 965905
Testing of Kitchen Knives
Introduction
The four ceramic kitchen knives, illustrated in Figure 1, were received for evaluation with regards to BS EN ISO 8442-5: 2004 Materials and articles in contact with foodstuffs –cutlery and table hollowware – Specification for sharpness and edge retention test of cutlery.
Received Knives
1 x 13 cm Kyocera 1 x 16 cm Forever 1 x 15 cm Unknown 1 x 15 cm Eagle
Figure 1
All information emanating from this Association is given after the exercise of all reasonable care in its preparation and issue but is provided without liability in connection with its application or use in particular circumstances Registered in England No 739777, with limited liability Sheet 2 of 6 CATRA Report Number: 965905
Sharpness and Edge Retention Test - BS EN ISO 8442-5: 2004
An edge test was carried out on each knife using CATRA's automatic edge tester in accordance with BS EN ISO 8442-5: 2004 - Materials and articles in contact with foodstuffs - cutlery and table hollowware, Part 5 - Specification for Sharpness and Edge Retention Test of Cutlery.
The blade is made to reproduce a cutting action, by forward and reverse strokes, against a pack of synthetic test card containing 5% quartz. Performance of the blade in terms of distance cut through the pack of card on each cycle is measured throughout the duration of the test. The apparatus is computer controlled and fully automatic.
The ICP, the Initial Cutting Performance (measured in mm), is the total depth of card cut during the first three cutting strokes and is a measure of the initial sharpness of a blade.
The TCC, the Total Card Cut (measured in mm), is the total depth of card cut during the test, and is a measure of the ability of a knife blade edge to resist wear throughout its useful life.
Since the majority of plain edge knives are steel they are tested for 60 cycles and the standard requires a minimum of 50 mm card cut to pass the ICP and a minimum of 150 mm for the TCC.
CATRA state that a knife is blunt if it no longer cuts 5 mm of card.
Ceramic knives are harder and resist wear to a greater extent therefore they have been tested for longer with the following results:
Results
Tabulated below are the ICP and TCC for the 4 blades after 1000, 2000 cycles and/or until they no longer cut 5 mm of card.
Cutting ability
TCC TCC TCC Knife ICP (mm) 1000 cycles 2000 cycles Under 5 mm Eagle 69.3 7570 8052 8052 Kyocera 95.7 8873 9379 9379 Unknown 54.9 6704 6704 6704 Forever 131.1 17110 26614 35732
The graphs for 1000, 2000 cycles and until cutting less than 5 mm of card for all knives are given in Figures 2, 3 & 4 respectively.
Hardness
The hardness of the blades was achieved using the Vickers method with a 10 kg load.
Eagle 1168 Hv Kyocera 1206 Hv Unknown 1332 Hv Forever 1310 Hv
CATRA, Henry Street, Sheffield S3 7EQ. Tel:++44 (0)114 2769736 Fax: ++44 (0)114 2722151 E-mail: [email protected] Sheet 3 of 6 CATRA Report Number: 965905
Comments
Listed below are other factors that influence the sharpness and edge retention of a knife blade:
1 Angle of the cutting edge 2 Thickness of the blade 1 mm back from the cutting edge 3 Surface finish ground or polished
Conclusion
The Forever knife performed considerably better than the other ceramic kitchen knives.
G E Gregory B Eng (Hons) CEng MIMMM Project Metallurgist
CATRA, Henry Street, Sheffield S3 7EQ. Tel:++44 (0)114 2769736 Fax: ++44 (0)114 2722151 E-mail: [email protected] Sheet 4 of 6 CATRA Report Number: 965905
CATRA - Sharpness & Wear Results for Ceramic Knife Blades After 1000 cycles Figure 2 BS EN ISO 8442-5: 2004 45
40
35
Eagle 30 Kyocera Unknown
25 Forever
20 Card Cut (mm)
15
10
5
0 1 30 59 88 610 639 668 697 726 755 784 813 842 871 900 929 958 987 117 146 175 204 233 262 291 320 349 378 407 436 465 494 523 552 581
Number of cycles
CATRA, Henry Street, Sheffield S3 7EQ. Tel:++44 (0)114 2769736 Fax: ++44 (0)114 2722151 E-mail: [email protected] Sheet 5 of 6 CATRA Report Number: 965095
CATRA - Sharpness & Wear Results for Ceramic Knife Blades After 2000 cycles Figure 3 BS EN ISO 8442-5: 2004 45
40
35
Eagle 30 Kyocera Unknown 25 Forever
20 Card Cut (mm)
15
10
5
0 1 59 117 175 233 291 349 407 465 523 581 639 697 755 813 871 929 987 1161 1219 1277 1335 1393 1451 1509 1567 1625 1683 1741 1799 1857 1915 1973 1045 1103 Number of Cycles
CATRA, Henry Street, Sheffield S3 7EQ. Tel:++44 (0)114 2769736 Fax: ++44 (0)114 2722151 E-mail: [email protected] Sheet 6 of 6 CATRA Report Number: 965095
Figure 4 CATRA - Sharpness & Wear Results for Ceramic Knife Blades Cutting Down to 5 mm of Card BS EN ISO 8442-5: 2004 45
40
35
Eagle 30 Kyocera Unknown 25 Forever
20
Card Cut (mm)
15
10
5
0 1
89 177 265 353 441 529 617 705 793 881 969 2025 2113 2201 2289 2377 2465 2553 2641 2729 2817 2905 2993 3081 3169 3257 3345 1057 1145 1233 1321 1409 1497 1585 1673 1761 1849 1937 Number of cycles
CATRA, Henry Street, Sheffield S3 7EQ. Tel:++44 (0)114 2769736 Fax: ++44 (0)114 2722151 E-mail: [email protected]