Basics for CNC Carbide Inserts Author : Date : 2/8/2013 1:20:51 AM
The first part of: Carbide Insert
1 Concepts; refractory metal compound (hard phase) and the bonding metal (binder phase), a composite material produced by powder metallurgy method.
Common carbides include: WC Tic Tac (tantalum carbide) NBC (niobium carbide)
Commonly used binder: Co Ni Fe
Carbide strength depends mainly on the content of cobalt.
Carbide of two main factors, including the strength and hardness, these two factors are mutually contradictory. With the strength increase in hardness may be reduced, carbide models distinguish the distinction of the different nodes of these two parameters.
2 Carbide characteristics
1) high hardness, high wear resistance
2) high modulus of elasticity
3) high compressive strength
4) chemical (acid, alkali, high temperature oxidation stability)
5) low impact toughness
6) a low coefficient of expansion, thermal conductivity, electrical conductivity, and iron and its alloys similar
Carbide brittle, not cutting;
Compared carbide tool steel has the following advantages:
a increase the service life of the tool;
b improve cutting efficiency and labor efficiency;
c improve workpiece finish and accuracy;
d can be processed heat-resistant alloys are difficult to process high-speed steel, efficiency alloys, special hardware difficult to machine materials such as cast iron.
3 concept;
Continuous cutting: cutting in the cutting process, the cutting edge is always in contact with the workpiece.
Intermittent cutting intermittently: in the cutting process, the cutting edge in contact with the workpiece cutting.
High-speed cutting: speed to be several times higher than conventional cutting parts machined to an advanced technology.
4 CNC blade precision level
Common tool materials, high-speed steel, carbide, coated carbide, ceramics, cubic boron nitride and diamond. Type of workpiece material: steel P, stainless steel M, cast iron K, non-ferrous metal N, high-quality alloy S, hardened material H.
Level of precision CNC blade:
Eg type CNMG120408, the third letter M represents the manufacturing precision of the blade.
Part II: cemented carbide composition, structure, and performance
1 Carbide mainly includes the following sections
Wc-wearable phase
Co-toughness phase
Tic Tac Nbc-hard phase
Crc Vc (vanadium carbide) - suppress phase
Structure: two-phase structure and three-phase organization, the three organizations determine the quality of the carbide.
Cemented carbide substrate (skeleton) + The structure and shape of the blade (flesh) + coating (skin)
2 Carbide classification
1) tungsten cobalt (WC + Co) Carbide (YG) is equivalent to Class K
2) class tungsten titanium cobalt carbide (WC + TiC + Co) (YT) type is equivalent to Class P
3) tungsten, tantalum, cobalt, carbide (WC + TaC + Co) (YA) is equivalent to Class G
4) the tungsten titanium-tantalum cobalt class (WC + TiC + TaC + Co.)) carbide (YW) is equivalent to Class M
P class steel processing
Class M stainless steel is difficult to machine materials
K-class cast iron and non-ferrous metals
Class G mine geological tools
* Performance indicators: density, hardness, flexural strength, coercivity, cobalt magnetic.
3 carbide production process
The traditional process flow
The CNC blade of process
Ingredients → milling → spray drying → → Hair seized suppress → sintering → check → passivation → cleaning → coating → grinding → half into inspection
Mixture Preparation: ingredients?
And prepared by a few links (ingredients - wet grinding - dry - sifted)
The ingredients group distributed evenly decision to suppress the quality of the performance and the entire product
4 alloy production
Wet grinding of the media?
Alcohol ethane acetone
Repression concepts: the mixture, and then fill in the die hole presses pressurizing the powder form of the mixture is extruded into a product having a certain shape and size
The repression is usually divided into three stages?
1) briquette density with increasing pressure increases rapidly; drastically reduced porosity.
2) briquette density increased slowly, the particles elastically yielding just pore eliminate a large number of Phase 1 and continue to pressure.
3) the pressure increase could reach the yield limit and ultimate strength of the material powder, the powder particles produced at this pressure the plastic deformation or brittle fracture. Due to brittle fracture of the particles to form the pieces to fill in the pores, the the briquette density increases.
Grinding concept: using a grinding tool and an abrasive is removed from the workpiece finishing methods (grinding of the surface of the layer of very thin layers: abrasive to a higher speed rotation, the method of machining on the workpiece surface.)
Grinding; face grinding peripheral grinding, profiled grinding, machining centers.
Grinding process called, not just grinding process.
Passivation processing (rounded) definition: the cutting edge of the blade to some processing in order to increase the strength and tool life of the cutting edge.
Head to passivation processing and role;
Improve the strength of the cutting edge and improve tool life and cutting process stability;
2 to eliminate the microscopic gaps and cracks;
3 smooth edge, reducing burr;
4 to improve the coating application;
Four edge approach: chamfering plus rounding, chamfering, rounding, chamfering ie not round
Surface processing is divided into three categories: surface modification, surface coating, surface treatment
Coating concept: in the surface of a base of strength and toughness is preferably cemented carbide or high speed steel (HSS), by a vapor deposition method of coating a thin layer of good wear resistance refractory metal or non-metallic compound
Role: coated tools have a high surface hardness, wear resistance, chemical stability, heat resistance to oxidation, low coefficient of friction and low thermal conductivity characteristics of uncoated tools to improve tool life 3 to 5 times higher than comparable cutting , increase the cutting speed by 20% to 70%, improve machining accuracy 0.5 to 1, to reduce tool consumption costs 20% to 50%.
Production commonly used coating methods, there are two: the physical vapor deposition (PVD) and chemical vapor deposition (CVD) method
The third part of CNC blade product knowledge
CNC tool classification;
Turning Tools
Milling tool
Drilling tools
Tools System
2 the structure of the tool comprising: a cutter body, blades, and the clamping mechanism
The main way of clamping mechanism including S class screw P class lever, N, dual solid (for roughing or finishing requirements)
3-blade shape (The following are a few common models)
C 80 ° rhombic
D 55 ° diamond
V 35 ° rhombic
K 55 ° parallelogram
R round
S 90 ° square
T 60 ° equilateral triangle
W 80 ° hexagonal
4 trough
What is the significance of the off quiet groove?
Cut quiet preset curl flow and break. Make good crumbs shaped form acceptable in order to achieve effective control of the chip material worries. Effective control tool sharpness, to ensure that the wear resistance of the tool, the cutting force and the tool tip strength achieve the best results.
Chipbreaker shape following figure
Constant relief angle and the rake angle in the case of mountain width of the blade sharpness to decide.
Sharp and intensity of the two elements is a contradiction, between these two points to find the best combination of point design.
5 CNC blade classification
By material is divided into the following categories
1) Carbide CNC blade
2) carbide coated inserts
3) metal ceramic blade
4) non-metallic ceramic blade
5) superhard blade
The deep sub: carbide coated inserts can be used for dry cutting, the far-reaching impact of this type of work
PVD and CVD both coatings compared the advantages and disadvantages:
Applications are divided into the following broad categories:
Car sales blades
1) Ordinary turning inserts
2) Aluminum turning inserts
3) cut grooving turning inserts
4) thread turning inserts
5) Turning blade wiper
6) gravity turning inserts
7) copy turning blades
8) double-sided slot the light load roughing blade
9)
Note: in the form of the blade is the demand generated by the first-tier manufacturers in the production process to reflect the equipment manufacturers, and ultimately a variety of blade types. Should the needs of students, and change as circumstances change.
Sided grooves (roughing with negative blade) and why?
Sided slot (finishing with positive blade) Why?
Roughing requires positioning a solid blade strength, with double-sided slot is positioned adverse. If the positive blade will reduce tool life.
Deep points; Aluminum turning inserts (such blade coating passivation)
To ensure sharp and smooth chip evacuation so the blade shape blade width, front and back angle should also increase.
FEATURES: a coating passivation does not guarantee the the sharp b rake face very smooth
