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Knife Sharpening

Knife Sharpening

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Knife Sharpening

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  1. Knife Sharpening Sheldon Becker Southern Qld Institute of TAFE

  2. Poultry Processing Using knives continuously relates up to 50% of injuries (lacerations or muscle strains)

  3. Meat processing In the red meat industry up to 68% of injuries Of which 32% is cuts & lacerations

  4. Blunt Knives - are frustrating to use - can lower the quality of the product - often the cause of accidents - can be responsible for Occupational Overuse Syndrome (OCC) type injuries Who likes sharpening knives?

  5. Blunt knives can lead to unsafe practices • Poor running point – Running hand up blade • Pushing when blunt– Physically pushing and dragging the knife • Over stretching – Not maintaining balance properly, not keeping up • Violent or sudden movements – Stabbing or hacking at the product • Deterioration – Tiredness, hands and arms are can cramp up & get sore • Emotional and Physical well being – Facing another day with a blunt knife is not fun, social issues impacting on your work • Incorrect steeling practices – Back steeling, uneven angles, not checking steeling action, grip on knife, and steel is incorrect • Repetition work – Continuously making additional cuts or doing same task

  6. How have most people here learnt how to sharpen a knife? • Maybe from a fellow worker • Some workplaces have a mentor/ trainer • Watching others sharpen their knives • Taught themselves through trail and error

  7. Benefits of Knife Sharpening training Would see a reduction in: • Knife related injuries • Tendonitis • Carpel Tunnel • Tennis Elbow • Musculoskeletal injuries • Time off work • Improved production • Job becomes easier

  8. Training Who to start with: • staff new to the plant or industry • all staff demonstrating poor technique • staff with high incidents of knife injuries • staff struggling with the job • staff open to change

  9. Key points to lessen knife injuries • Warm up before starting – Follow recommended stretching practices. • Use a good shape blade – Choose the correct knife for the job. • Work with a rhythm – Minimise your blows or cuts and work more efficiently • Take breaks – Do not work through breaks - Take breaks as required

  10. Identifying the symptoms of musculoskeletal injuries • Muscle discomfort • Fatigue • Aches and pains • Soreness • Hot feelings • Cold feelings • Muscle tightness • Numbness tingling • Muscle weakness

  11. Occupational Overuse Syndrome (OOS) • OOS usually develops over a period of time. • Caused or aggravated by :- - sustained or constrained postures - repetitive movements • One explanations for OOS is that it is caused by the muscles being held too tight for long periods of time

  12. NZ Grip force study Independent study found • 20% of the process workers have a reasonably good knife • 40% had an average knife • 40% had a knife that was insufficient for the task

  13. NZ Grip force study • Study also found the tighter the grip on the knife the less blood flow in the hand and arm. • The size of the hand holding the knife is also a factor on grip force.

  14. The knife length The length and weight test used to determine grip force • Place a 0.5 kg weight 13 cm, 15 cm, 17 cm distances along the steel or bar. • The grip force has increased as the length of each knife increases. • Longer blades require a greater grip force than shorter blades.

  15. Cutting Force • A sharp knife requires 30% less force to cut than an average knife • A sharp knife also enables a task to be performed 30% faster, and requires 30% less grip force • A processing room with consistently sharp knives produced a 1 to 3 % greater yield than the same room with normal levels of sharpness • By testing a knife we can now tell how much cutting force is required to cut with that knife • We can now calculate how much cutting force a worker is using over a days work

  16. Sharpness Tester

  17. Score

  18. Example • A worker boning forequarters all day would use approx6400 cutting strokes a day • A sharp knife has a cutting force of 1.1kg per cutting stroke • 1.1kg x 6400 strokes = 7.40 tons of daily force • If we multiply 6400 strokes with a 15kg blunt knife, we end up with a daily force of 96 ton • This equates to 88.6 tons more cutting force than a sharp knife

  19. NZ experience Photo courtesy of Anago Ltd

  20. Equipment use to sharpen and maintain knives • Knives and their correct storage equipment • PPE (cut resistant gloves, safety glasses) • Grinding wheels (grinders) • Sharpening stones • Steels • Washing & sterilising facilities

  21. Safety Equipment used when sharpening a knife Cut resistant Safety glasses

  22. Choose a knife suitable for the task. Skinning Knife Curved boning knife Straight boning knife Slicing knife

  23. Knife Shapes Convex Flat Hollow Concave

  24. Equipment used to shape/sharpen knives Sandstone wheel Belt Grinders

  25. Grinding the knife

  26. Sharpening the knife Sharpening or honing stone are used to establish a sharp edge on a knife.

  27. Methods used to sharpen a knife Setter Sharpening stone

  28. Issues • Evenly grinding of knives to the correct shape - both sides - from tip to heel • Evenly sharpening knives (correct edge) - both sides - from tip to heel • Evenly & effectively steeling knives “It all about the correct angles”

  29. Hollow Grinders Used by authorised personal only

  30. Knife setter

  31. Knife setters

  32. Creating a feather Stand on handle side of knife when stoning. Place thumb and forefinger on stoning rod & other hand on stoning bar. Work from tip to heel, then heel to tip to develop a feather. Turn knife over & repeat process

  33. Removing feather Start by placing heel of stone on the knife tip. Pull the stoning rod straight back over the cutting edge overlapping the stone on each stroke. Turn knife over & repeat Run the knife through a plastic block (Feathering Block)

  34. Finishing strokes Place the heel of the stone on the tip of the knife and pull stoning rod back toward the knife handle 6 times. Turn knife over and repeat process

  35. Steeling a knife • To remove any burrs from the edge • To straighten (centre) the edge

  36. Types of Steels

  37. Holding a knife Make sure you tuck your little finger on the side of the handle Make sure the knife butt sits in the groove of your thumb and forefinger palm The knife should be in a straight line with your arm

  38. Steeling a knife Check arm, steel and knife are square and in line. Knife handle centre of wrist Hold steel as above with the thumb tucked behind steel

  39. Storing Knives Knives must be stored in the pouch when not in use

  40. Testing bite Bites left Bites right Bite Stick Stick Both sides of the knife are sharp

  41. Testing bite Bites left Slides right Bite Stick Stick Bite left only knife is turned to the left Steel left side of knife the bite side.

  42. Testing bite Slides left Bites right Bite Stick Stick Bite right only knife is turned to the right Steel right side of knife the bite side

  43. Testing bite Slides right Slides left Bite Stick Stick Slides both ways, there is no bite, knife will need to be steeled again or sharpened

  44. Safety Equipment when using a knife Cut resistant Mesh

  45. Safety Aprons

  46. Now That’s A Knife

  47. Acknowledgements Southern Qld Institute of TAFE would like to acknowledge contributions by:- • Big Bay Skills Training Ltd • Argus Realcold Limited • Teys Bros Pty Ltd

  48. Question? Thankyou