What are the difficulties in drilling stainless steel?

The difficulties of stainless steel material processing mainly include the following aspects:

  1. High cutting force and high cutting temperature

This type of material has large strength and large plastic deformation during cutting, so the cutting force is large. In addition, due to the poor thermal conductivity of the material, the cutting temperature is increased, and the high temperature is often concentrated in the narrow area near the cutting edge, which accelerates the tool wear.


  1. Severe work hardening

Austenite stainless steel and some high temperature alloy stainless steel are Austenite structure. These materials tend to be hardened when machined, often several times as much as plain carbon steel. The cutter is cut in the hardened area to shorten the tool life.


  1. Easy to stick the tool

Both Austenite stainless steel and Martensite stainless steel have the characteristics of strong and tough chip and high cutting temperature. When the strong and tough chip flow through the front surface of the cutter, the phenomenon of bonding, welding and other adhesion will occur, affecting the surface roughness of the processed parts.


  1. Tool wear is accelerated

The above materials generally contain high melting point elements, large plasticity and high cutting temperature, which make the tool wear faster and the tool wear and change frequently, thus affecting the production efficiency and increasing the tool use cost.

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Problems encountered during the operation of the alloy bit and its solution

What kind of material is suitable for what kind of tool?

What kind of material is suitable for what kind of tool?


Problem Solution
The front end of the alloy bit is broken Aimed at the bit again
Repair with a drill bit grinder
Improve stability, re-clamp parts, shorten overhang of alloy bit
Check speed/feed
The outer diameter of the alloy bit is worn Aimed at the bit again
Improve stability, re-clamp parts, shorten overhang of alloy bit
Check speed/feed
Repair with a drill bit grinding machine
Oversize/undersize holes To aim at tungsten steel drill bit
To reduce feed
Check speed/feed
The alloy bit is clogged with chips in chip removal tank Increase coolant flow, clean filter, clean bit coolant hole
To reduce feed
Improve stability, re-clamping the parts, shortening the overhang of alloy bit
Check speed/feed
Increase speed
vibration To reduce feed
Improve stability, re-clamping the parts, shortening the overhang of alloy bit
Check speed/feed
A small crack in the cutting edge Repair with a drill bit grinder
Aimed at the bit again
Check the carbide number
Increase speed
Hole asymmetry To reduce feed
Improve stability, re-clamp parts, shorten bit overhang
Check speed/feed
Alloy tool has short life Increase coolant flow, clean filter, clean bit coolant hole
Improve stability, re-clamping the parts, shortening the overhang of alloy bit
Check the carbide number
Check speed/feed

What are the advantages of CVD diamond coated tool?

Chemical Vapor Deposition is called CVD. Diamond coating has many excellent properties such as high hardness, high thermal conductivity, low friction and low expansion coefficient.

In the processing of brittle materials such as graphite and carbon fiber composite materials, it has become the surface coating of cutting tools and has shown excellent performance in improving tool life and processing quality.

The selection of diamond coating thickness is not “the thicker the better”.

How many types of milling cutter according to purpose?

With the improvement in wear resistance, the quality of diamond coating is more important than that of thickness.

After continuous testing and verification of various tool materials, the service life of CVD diamond coated tool is 8 ~ 10 times of that of cemented carbide tool. The allowable cutting speed of CVD diamond coated tool is 2 ~ 3 times higher than that of hard alloy tool.

CVD diamond coated tool has sharp cutting edge and good consistency, low friction factor, and can realize high speed and precision machining of thin-walled graphite mould under high speed and low feed. Meanwhile, the service life of CVD diamond coated tool is longer among many tool materials.

The selection and application of diamond coated tools are mainly based on the properties of workpiece materials and the requirements of machining quality.

Note: When the coated bit is repaired by drill bit grinding machines, the worn coating is irreparable.

Introduction to the hole cutting tools which commonly used in NC machining

Hole cutting tools used in NC machining are:

  • High speed rake angle oil hole twist drill;
  • Helical groove Centre Drill;
  • 3 – flute Solid Carbide Drill;
  • S-type carbide drill bit;
  • Indexable carbide bit;
  • Carbide double edge boring tool;
  • Carbide single edge fine boring tool

In addition, some special industries of NC machining have their own often used hole tool. Such as the printed circuit board industry micro-cemented carbide integrated drill, refrigerator compressor industry integrated cemented carbide precision reamer and step twist drill.

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Compared with the tools used in ordinary machine tools, CNC tools have many different requirements, mainly with the following characteristics:

(1) good rigidity (especially rough tool), high precision, low seismic and thermal deformation; Good interchangeability, easy to change tools quickly;

(2) high life, stable and reliable cutting performance;

(3) the size of the tool is easy to adjust, so as to reduce the adjustment time of tool changing;

(4) the tool should be able to reliably break the scrap or roll the scrap, so as to facilitate the scrap removal;

(5) serialization and standardization to facilitate programming and tool management.


When your tool is blunt, choosing to use a tool grinder can be very useful. Our drill bit grinder can repair all kinds of tools (drill bit re-sharpener, end mill re-sharpener, screw tap re-sharpener, lathe tool grinder, saw blade sharpener, universal(all-purpose) cutter grinder, universal(all-purpose) tool grinder, chamfer, air tapping machine, gear chamfering machine, universal(all-purpose) head, rotary table, etc. ). If you want to buy our products, please send us your requirements and cutter parameters first. We will help you choose the corresponding model.

What are the machining methods of thread?

Thread cutting

Generally refers to the use of forming tools or grinding tools in the workpiece thread processing methods, mainly including turning, milling, tapping, thread sleeve, grinding and whirlwind cutting.

When turning, milling and grinding threads, the drive chain of the machine tool ensures that the tool, milling cutter or grinding wheel move a guide path accurately and uniformly along the workpiece axis at each turn of the workpiece. In tapping or threading, the tool (tap or die) rotates relative to the workpiece, and the tool (or workpiece) is guided axial by a threaded groove formed first.

The forming tool or thread comb tool can be used to cut the thread on the lathe. Because of the simple structure of the tool, it is a common method to produce single and small batch of threaded workpieces. Using the thread carding tool to cut the thread, the production efficiency is high, but the tool structure is complex, only suitable for the short thread workpiece of turning fine teeth in medium and large quantity production.

The pitch precision of turning trapezoid thread can only reach 8~9 grades (JB2886-81).

The productivity or precision of machining threads on a specialized threaded lathe can be improved significantly.

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Q&A when buying PG-13A and PG-13A

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PURROS PG-13D patent drill bit re-sharpener grinder


Q: what’s this little machine for?

A: this little machine is specially designed for grinding ordinary twist drill.


Q: how many ranges of diameters can it grind?

A: the grinding range of this model pg-13d is 3-13mm.


Q: do you have a drill bit grinder with a larger grinding range? For example, the grinding diameter reaches 20mm.

A: yes, different types of drill bit grinders have different diameters for grinding. For example, the grinding range of pg-13 is 3-13mm, the range of pg-26 is 13-26mm, and the grinding range of pg-g3 is 3-26mm, and the maximum grinding range can be 3-32mm by selecting machine parts.


Q: what’s the difference between model A and model D?

A: the type A grinder can only grind the land angle and lip relief Angle of the drill bit, but cannot repair the chisel edge of the drill bit. Such A drill can only drill holes, and the accuracy error is relatively large. The type D drill bit grinding machine can grind the land Angle and lip relief Angle of the drill bit, and also repair the chisel edge of the drill bit, so that the drill bit has accurate drilling and easy chip removal.


Q: is this grinding wheel on the market?

A: yes, our grinding wheel is a national standard. It is sold in the market.


Q: how long is the warranty on your machine?

A: because we have small equipment, the vulnerable parts are motors and grinding wheels. The grinding wheels are international standard and can be bought in the market, so our machine has a one-year warranty.

How to reduce the abrasion of drill bit?

The drill bit is arguably the most commonly used key component, and it is easy to wear out. How to reduce the abrasion of drill bit is very important?


What is abrasion?

The wear caused by the two components squeezing each other and causing relative motion.

For example, between the tool tip and milling and planning materials. In the process, tiny particles on the surfaces of the two components are detached from the elements.

Common causes of tool wear:

All components of the tool are more or less worn by milling and planing materials.

If a single component is damaged, such as blade tip, steel tool body, gasket or spring, the entire tool should be replaced. This prevents damage to the relatively expensive tool holder system, and the replacement of the tool holder system is more complex.


Common tool wear includes the following reasons:

  1. Incorrect installation;
  2. Use components from different manufacturers;
  3. Incomplete cleaning: milling and planing materials on the tool plate and continuous accumulation;
  4. Choose the wrong tool (different type of machine should choose different type of tool);
  5. The sprinkler system in the housing of the milling and planing drum is short of water supply.

How to reduce tool wear and tear?

Tool wear is not entirely avoidable, but it can be minimized.

  1. Sufficient water supply is the basic premise to ensure the normal rotation of the tool.
  2. Select the right tool according to milling and planing materials, which can also optimize the use and reduce wear.
  3. Pay attention to daily thorough cleaning;
  4. Regularly check the tool, and timely detect and deal with the wear and tear or damage of components;
  5. Regularly maintain and inspect the sprinkler system;
  6. Select milling tools suitable for working conditions.

Correct installation to reduce wear and tear:

  • Before installation, check whether there is any foreign matter in the inner diameter of the tool holder and confirm whether cleaning is necessary.
  • Use proper tools (copper hammer or pneumatic insert tool) to prevent damage to the tip.
  • Manually check the tool rotation (turn the tool by hand).
  • Only proper maintenance tools can minimize the wear and tear of key components.

This greatly saves the cost and ensures the efficient operation of the machine. In the daily maintenance, we recommend our drill bit grinding machine. This tool can be used to repair your drill bit in case of wear and tear. Allow your drill to be reused and the life of the drill is increased, and your money is saved.

How to select the attachment of universal tool grinder for different cutting tools grinding?

PG-600, PG-600F, PG-6025 are universal tool grinder from PURROS Machinery, which can be used for widely cutting tools sharpening, such as peripheral cutting edge of end mill, side cutting end mill, arc cutting tools, R-type cutter, Ball-type cutter, R-type lathe tool, tapered end mill, gun-drill bit, deep hole drill bit, regular drill bit, step drill, screw tap, chamfer cutter, end mill, shaft, regular turning tool, CNC lathe tool, lathe roughing tool, planed cutting tool, lathe tools at all angles, hobbing cutter, circle cutter, circular forming cutting tool, and also can be used for cutter fixed center.

For grinding attachments, the models are: 50D, 50E, 50Q, 50K, 50S, 50C, 50H, 50B
For selecting the attachment to match grinding tools, there are some issues for each user, so now, PURROS Machinery list all of details as below:


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PURROS end mill grinding attachment 50D 50D Attachment
Used for front face and peripheral cutting edge of end mill, side cutting end mill, etc.
Grindable range: φ3-28;
Shaft model of end mill: straight, MT 4
Grindable Tools End Mill
PURROS end mill grinding attachment 50E 50E Universal Attachment
Including the all the functions of 5D, besides, arc cutting tools, R-type (Ball-type) cutters, R-type lathe tools, tapered end mills, etc.
Grindable range: φ3-28;
Shaft model of end mill: straight, MT 4
End Mill Supplier, Cheap End Mill for Sale
PURROS end mill grinding attachment 50Q 50Q Attachment
Used for Gun-drill Bits & Deep Hole Drill Bits, adopted 6-jaw chuck design to ensure accuracy of the center.
Grindable range: φ4-33;
Drill Bit for Deep Holes
PURROS end mill grinding attachment 50K 50K Attachment
Used for drill bits, step drills, screw taps, chamfer cutters, end mills, shafts, etc.
Grindable range: φ3-50;
Drill Bit, Step Drill Bit, Screw tap, Chamfering Cutter, End Mill, Side Cutting Tool
PURROS end mill grinding attachment 50S 50S Attachment
50S is a 3-jaw chuck attachment, and with a high-speed motor; Also it is a universal attachment.
Grindable range: φ3-100;
Metal Cutting Tools
PURROS end mill grinding attachment 50C 50C Lathe Tool Attachment
Used for regular turning tools, CNC lathe tools, lathe roughing tools, planed cutting tool, and lathe tools at all angles.
CNC Lathe Tools
PURROS end mill grinding attachment 50H 50H Universal Attachment
Used for side cutting end mill, hobbing cutter, circle cutter, and circular forming cutting tools.
hobbing cutter
PURROS end mill grinding attachment 50B 50B Fixed Center Attachment
Used for all of tools needs to be fixed center with other attachments during grinding.
Base of Universal Tool Grinding Machine Machine Base (Also Tool Cabinet)
It is a special and multipurpose machine base, which can be place the grinder, and tools and machine parts can be collected in the cabinet, etc.
Universal Tool Grinding Machine with the Base

What kind of material is suitable for what kind of tool?

Determine the material of the tool according to the machining type and workpiece material. It is a common knowledge in the whole machining industry to match tool materials with workpiece materials. But not everyone knows how many conditions this so-called match will satisfy. Next, we will introduce ‘how tool materials and workpiece materials can match mechanical, physical and chemical properties’.

How do the mechanical properties of tool materials and workpieces match?

The mechanical properties are mainly designed for the strength, toughness and hardness of the tool and workpiece. All kinds of tool materials are arranged in order of bending strength from strong to weak: high-speed steel, hard alloy, ceramic tool, diamond and cubic boron nitride tool. In order of toughness from high to low: high speed steel, hard alloy, cubic boron nitride, diamond and ceramic tool; In order of hardness from high to low: diamond tool, cubic boron nitride tool, ceramic tool, hard alloy and high speed steel.

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How should we distinguish the different helix angle of end milling cutter?

The helix angle of end milling cutter can be divided into 30°, 45°, 50° etc. There are many kinds of them. Now let’s look at how to distinguish between them.

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End mill sharpening machine


  1. The function of helix angle

The more helix angle of end milling cutter, the longer the contact length between workpiece and cutting lip will be. In this way, the load of cutting lip per unit length can be reduced, so the tool life can be extended. However, at the same time, the cutting resistance will be increased, so it is necessary to consider the use of clamping rigid high tool shank.


  1. The choice of helix angle

For hard cutting materials of stainless steel with low thermal conductivity and having a great influence on tip heat exposure, large helix angle of end milling cutter is adopted for cutting, which is conducive to extending tool life. In addition, the features of the finish plane are changed by helix angle. For example, when smooth finish machining is needed, sometimes we can use big helix angle of end milling cutter. However, when using the large helix angle of end milling cutter, the cutting resistance will be increased, and the right helix angle cutter will be forced to break out. Therefore, corresponding measures must be taken, such as holding the rigid high tool handle. Although the rigidity of the tool can be ensured, in the case of low rigidity thin plate machining and other workpieces, small helix angle of end milling cutter is sometimes used.


  1. 50 ° helix Angle of the spiral in profile processed by end milling cutter:

Multi – edge design, good rigidity of the tool, can minimize the amount of side cutting.

The tip of the blade is protected by the tip of the blade, which can prevent the tip from falling off.


  1. 60 ° helix Angle of end milling cutter is suitable for the high speed cutting hard cutting material such as SUS304:

For difficult cutting materials with low thermal conductivity and easy to increase the temperature of the tip during cutting, the unique shape of the blade can inhibit the influence of cutting heat on the tip.


  1. Finish milling cutter for high-speed machining:

USES 45 ° helix angle and unique groove shape, at the same time to realize high speed machining, improving wear resistance. The surface roughness is good after machining with fine tooth groove.

Use ALC coatings with good lubricity and heat resistance (heat-resistant temperature of 1100 ℃).


Our end mill grinder can intelligently handle the helix angle problem. If the end milling cutter is sharp, you can choose our end milling sharpening machine to repair.