---
title: "Grinding wheel specification and selection"
subject: "Manufacturing and Production Processes"
chapter: 8
key: "semester_4/manufacturing_and_production_processes:grinding-wheel-designation-selection"
source: https://www.bctengineer.com/q/semester_4/manufacturing_and_production_processes/grinding-wheel-designation-selection
site: BCT Engineering
---

# Grinding wheel specification and selection

Manufacturing and Production Processes · Chapter 8: Material Removal Processes: “Abrasive and Non-Traditional”

- Asked in: year not given, 5 marks
- Video: [grinding wheel specifications explained (English)](https://www.youtube.com/watch?v=uI1k7VldMus) — shop and math
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/manufacturing_and_production_processes/grinding-wheel-designation-selection
- Whole chapter: https://www.bctengineer.com/md/semester_4/manufacturing_and_production_processes/chapter-8

## Question

Explain the standard marking system of a grinding wheel with an example, such as A 60 K 5 V. What are glazing and loading of a grinding wheel? How are truing and dressing done?

## Short answer

The designation A 60 K 5 V indicates aluminium oxide abrasive, grit 60 (medium), grade K (medium hardness), structure 5 (medium spacing), and vitrified bond. Glazing is a smooth shiny surface from blunt grains (grade too hard); loading is pores clogged with chips (soft ductile metals). Truing restores shape and runout; dressing exposes sharp grains.

## Answer

A grinding wheel is a bonded mass of abrasive grains. Each grain acts as a tiny cutting tool, and the wheel renews itself as the dull grains break out and fall away.

#### Standard marking, example A 60 K 5 V

```text
  A     60     K      5      V
  |     |      |      |      |
abrasive grit  grade structure bond
```

| Letter or number | Meaning | Here |
|---|---|---|
| Abrasive | A = aluminium oxide, C = silicon carbide, B = CBN, D = diamond | Aluminium oxide: steels |
| Grain size | Grit number (coarse 10-24, medium 30-60, fine 70-180, very fine 220+) | 60 = medium |
| Grade | Hardness, A (soft) to Z (hard); the strength of the bond | K = medium |
| Structure | Spacing of grains, 1 (dense) to 15 (open) | 5 = medium |
| Bond | V = vitrified, S = silicate, R = rubber, B = resinoid, E = shellac | Vitrified |

#### Selection guide

- Steel and soft metals use aluminium oxide; cast iron, carbide and non-ferrous use silicon carbide.
- Hard materials need a **soft** grade so that dull grains drop out; soft materials need hard grades.
- Fine grit for good finish; coarse grit for fast removal.
- Wide contact area or soft material needs open structure.

#### Glazing and loading

- **Glazing:** the abrasive grains become blunt and the wheel surface turns smooth and shiny because the grade is too hard. Cutting efficiency falls, heat and burning appear.
- **Loading:** the spaces between the grains fill with chips of the work material (soft ductile metals such as aluminium or copper). The wheel cuts poorly.

#### Truing and dressing

- **Truing** restores the wheel shape and makes it run concentric, using a single-point diamond or a diamond roll.
- **Dressing** restores sharpness and exposes new grains by removing the glazed or loaded layer, using a dressing stick, star dresser (Huntington) or diamond. Often both are done together.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. In A 60 K 5 V, what does K represent?
   A. Grain size
   B. Structure
   C. Grade (hardness) of the wheel, medium
   D. Bond type
   Answer: C. A is abrasive, 60 grit, K grade, 5 structure, V bond; grade is the bond strength. (Key point: Designation)

2. Which grade should be used for grinding a hard material?
   A. A hard grade to resist wear
   B. Any grade, grade does not matter
   C. A very fine structure
   D. A soft grade so that dull grains drop out
   Answer: D. Hard work dulls grains fast; a soft grade releases them so new grains are exposed. (Key point: Selection)

3. What is the difference between glazing and loading?
   A. Glazing is blunt smooth grains from too hard a grade; loading is chips filling the gaps, common with soft ductile metals
   B. Glazing is chips in the gaps; loading is blunt grains
   C. Both mean the wheel breaks too fast
   D. Glazing occurs only with soft grades
   Answer: A. Glazing: shiny blunt surface. Loading: pores clogged with work material. (Key point: Glazing vs loading)

4. What is the purpose of truing?
   A. To expose new sharp grains only
   B. To restore the wheel shape and concentric running
   C. To make the grade harder
   D. To clean chips from the work
   Answer: B. Truing corrects shape; dressing restores sharpness. (Key point: Truing vs dressing)

## Related in other subjects

- [CI: mean weight loss of grinding balls](https://www.bctengineer.com/question.md?key=semester_5%2Fprobability_and_statistics%3Agrinding-balls-weight-loss-ci) — Probability and Statistics, chapter 6
- [Dressing of stones and methods](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Adressing-stone-methods) — Civil Engineering Materials, chapter 2
- [Standard rate filter, 3 MLD, 175 mg/l, NRC](https://www.bctengineer.com/question.md?key=semester_6%2Fsanitary_engineering%3Atrickling-standard-3mld-175-nrc) — Sanitary Engineering, chapter 7
- [Pelton wheel design (310 m, 5 m³/s)](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Apelton-design-310m-5cumec-specific-speed) — Hydropower Engineering, chapter 7