Grewin Bull – Type A Rotary Burr
The Most Common and Versatile Cylindrical Rotary Burr
Product Overview
The Grewin Bull Type A rotary burr is one of the most common and fundamental models in the rotary burr family.
Its cylindrical design makes it highly suitable for surface milling, corner cleaning, slotting, and chamfering.
When rapid and efficient surface milling or edge cleaning is required, the Type A double-cut rotary burr is often the first choice.
Key Features
- Tungsten carbide material: premium, highly durable, wear-resistant, and heat-resistant, with long service life.
- High-speed cutting: capable of machining hardened steels and other tough materials.
- Double-cut cross pattern: smooth cutting, fast chip evacuation, and high material removal rate.
- Versatility: widely applicable, making it the “all-rounder” tool in machining and mold manufacturing.
Processing Range
- Suitable for metals with hardness ≤ HRC55
- Carbon steel, alloy steel, stainless steel, etc.
Tool Structure
- Cylindrical flat head
- Double-cut cross fluting
- Designed for efficient, stable, and precise cutting
Application Fields
- Mold manufacturing
- Precision machining
- Aerospace
- Automotive industry
Technical Standards
- Complies with ISO 7755-1984(E) international standard
- Available in 12 models and 78 specifications
- Supports custom orders, trial production, and OEM manufacturing
Usage & Maintenance
- Safety: always wear goggles and cut-resistant gloves to protect against flying chips.
- Moderate force: avoid excessive pressure to prevent overheating or premature tool wear (reduce speed when using extended burrs).
- Cleaning: regularly remove debris to maintain sharpness and cutting efficiency.
- Speed control: optimized for high-speed operation; adjust RPM according to workpiece material.
Case Study – Rough Machining and Cleaning of a Narrow Deep Groove
Scenario: A plastic mold insert requires a narrow groove (6mm wide, 25mm deep) for a sealing strip. The groove must have vertical walls and a flat bottom.
Problem: The groove is too narrow and deep for large end mills, while EDM machining is inefficient.
Solution:
- Operator selected a 5mm Type A double-cut rotary burr, mounted on a high-speed die grinder.
- The cylindrical surface was used to mill the sidewalls, while the flat head was used to clean the groove bottom.
- Double-cut flutes enabled aggressive cutting with excellent chip evacuation.
Result:
- A groove with sufficient depth, vertical sidewalls, and flat bottom was efficiently produced.
- Follow-up fine finishing could be done with a single-cut burr if needed.
- Significant time was saved compared to traditional methods — a classic application of the Type A rotary burr.
