Rubbermaid Pelletizer Blades Case Study

We worked closely with a plant manager at the Rubbermaid Corporation to find out how the
costs of deep cryogenically treated
stood up to the costs of untreated knives. Our experiment and
calculations are based on the parameters we extracted from this trial.

Rubbermaid Pelletizer Blades Case Study

Cost Comparison | Treated vs. Non-Treated Knives

We compared the costs of a set of cryogenically
treated knives and untreated knives for a Nelmore grinder. The knives are D2 steel. Results and processing costs may
vary with the type of plastic, blade size, and number.


  1. Rubbermaid told us that untreated blades wear out
    after three months of service.
  2. Rubbermaid told us that cryogenically treated blades
    wear out in 24 months.
  3. The blade set costs $750.
  4. Labor to change blades is 4 hours.
  5. Cost to sharpen a set of blades is $100.00.
  6. Untreated blade sets can be sharpened ten
  7. Cryogenic processing of the blade set costs
  8. Labor charge out costs is $50.00
  9. Time basis for the calculation is one year.

The total cost of using the blades:

  1. The cost of the set(s) used minus any residual value
    at the end of the year
  2. Sharpening costs
  3. Labor costs

Blade Cost Calculations

Cost of Untreated blades per year:

750$Set ×
1Set11uses ×
1use3months ×
12monthsyear =

Cost of treated blades per year:

750$+500$Set ×
1set11uses ×
1use24months ×
12months1year =

Yearly Cost of Sharpening

The Yearly cost of sharpening untreated blades:

100$Sharpening ×
1Sharpening3months ×
1use3months ×
12monthsyear =

The Yearly cost of sharpening treated blades:

100$Sharpening ×
1Sharpening24months ×
12monthsyear =

Labor Costs for Changing the Blade

The Yearly cost of changing untreated blades:

50$Hour ×
4hoursChange ×
1change3months ×
12monthsyear =

The Yearly cost of changing treated blades:

50$Hour ×
4hourChange ×
1change24months ×
12monthsyear =

Treated Un)Treated
Yearly-Cost-of-Knives $57 $273
Yearly-Cost-of-Sharpening $50 $400
Yearly-Cost-of-Labor $100 $800
Totals $257 $1,473

Total Savings

The money saved by using cryogenic processing was $1216 per year /per

With over 65 grinders in one plastic molding plant, potential savings is over $79,000
per year. The money invested in processing the blades is returned in less than six months. More savings are
available if the screens are processed.

Contact Controlled Thermal Processing Today

If you want to improve the bottom line of your business by reaping the benefits of deep
cryogenic processing for
industrial and mechanical parts, or if
you’re interested in metallurgy consulting or purchasing your own cryogenic processing equipment, reach out to the
cryogenic specialists at CTP by
contacting us online or calling us at