Cutting vs grinding: which of the following is not classified as a cutting machine in solids processing?
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ADicers
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BKnife cutters
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CSlitters
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DTube mills
Answer
Correct Answer: Tube mills
Explanation
Introduction / Context:Solids size reduction equipment can be grouped by the dominant mechanism: cutting, compression, impact, or attrition. Correct classification aids in selecting equipment for specific materials (e.g., fibrous, ductile, brittle) and desired product forms (flakes, granules, powders).
Given Data / Assumptions:
- "Cutting" implies blade-based separation (shear) producing chips or slices.
- Tube mills are tumbling grinders with media, not blades.
- Dicers, knife cutters, slitters use edges to shear material.
Concept / Approach:Dicers, knife cutters, and slitters employ sharp edges and controlled clearances to produce precise cuts, common in food and polymer film processing. Tube mills (a form of ball/rod mill) perform comminution by cascading media that apply impact and attrition, producing powders instead of clean cuts.
Step-by-Step Solution:Identify cutting machines: dicer, knife cutter, slitter.Recognize tube mill: grinding device using media and rotation.Hence, "Tube mills" is the non-cutting option.
Verification / Alternative check:Tubular mills are widely used in cement and mineral industries for powder production, confirming they are grinding, not cutting, machines.
Why Other Options Are Wrong:Dicers/knife cutters/slitters clearly rely on blade shear mechanisms and are standard cutting equipment.
Common Pitfalls:Assuming any size reduction is "cutting;" many unit operations rely on impact or abrasion rather than shear.
Final Answer:Tube mills