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目前日期文章:201211 (5)

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切削液介紹-切削液的分類

在金屬切削加工過程中,使用切削液是為了降低切削時的切削力,及時帶走切削區內產生的熱量以降低切削溫度,提高刀具耐用度,從而提高生產效率,改善工件表面粗糙度,保證工件加工精度,達到最佳的經濟效果。

切削液的分類:

  • 非水溶性切削液
    主要是切削油。有各種礦物油,如機械油、輕柴油、煤油等;還有動、 植物油,如豆油、豬油等;以及加入油性、極壓添加劑配製的混合油。它主要起潤滑作用。
  • 水溶性切削液
    主要成分為水,並加入防銹劑,也可加入適量的表面活性劑和油性添加劑,使其具有一定的潤滑性能。
  • 乳化液
    由礦物油、乳化劑及其它添加劑配製的乳化油加95%~98%的水稀釋而成的乳白色切削液,有良好的冷卻性能和清洗作用。

切削液具有的功能性分類:

  • 冷卻性能:
    切削液通過它從它所能達到最靠近熱源的刀具、切屑和工件表面上帶走大量的切削熱,從而降低切削溫度,提高刀具耐用度, 並減小工件與刀具的熱膨脹, 提高加工精度。切削液要有較高的熱導率和比熱容,較高的汽化熱。一定的流量和流速。水的冷卻性能最好,油類最差,乳化液介於兩者之間。
  • 潤滑性能:
    金屬切削時,切屑、工件與刀具之間的摩擦可分為:乾摩擦、流體潤滑摩擦和邊界潤滑摩擦。切削液滲入到切屑、刀具、工件的接觸面間,粘附在金屬表面上形成潤滑膜,減小它們之間的摩擦係數、減輕粘結現象、 抑制積屑瘤,並改善已加工表面的粗糙度,提高刀具耐用度。潤滑性能取決於切削液的滲透性、吸附薄膜形成能力與強度等。水溶性潤滑劑(聚乙烯醇、甘油)。
  • 清洗性能:
    沖走切削中產生的細屑、砂輪脫落下來的微粒等,起到清洗作用, 防止加工表面、機床導軌面受損; 有利於精加工、深孔加工、自動線加工中的排屑。在切削液中採用非離子性表面活性劑(如平平加、太古油)和陰離子表面活性劑(烷基苯磺酸鈉、十二烷基硫酸鈉)進行複配,能起到顯著降低切削液表面張力的作用,達到清洗的目的。
  • 防銹性能:
    加入防銹添加劑的切削液,還能在金屬表面上形成保護膜,使機床、工件、刀具免受周圍介質的腐蝕。 切削液的使用效果決定於切削液的類型、形態、用量、使用方法等。水溶性防銹劑品種較多,通常分為有機防銹劑與無機防銹劑兩類。現在一般採用鉬酸鈉(0.05%)替代亞硝酸鈉,以減少污染;和有機防銹劑(硼胺)複合使用,達到很好的防銹效果。
  • 還具有防腐蝕性、抗菌性、防垢性、抗泡性、熱穩定性、無毒、無害、無刺激性氣味、不污染環境使用方便等作用。
資料來源:網路彙整

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Processing method of Tungsten Carbide End Mills – anticlockwise milling (up milling) and clockwise milling (down milling)

Milling is one of the most common and most widely used processing methods, and for roughing milling of the various structural components and fine milling is almost by end milling. There are two ways, clockwise and anticlockwise milling, according to the cutting direction. The movement of the cutting edge and work piece is in the opposite direction or same direction, divided into the two kinds of conventional milling and climb milling.

Anticlockwise Milling:

Milling direction and feed in the opposite direction (milling against the feed) is anticlockwise milling; chip caused from the bottom into upper, so we also call it as up milling; Since the traditional processing and milling mostly used this way, so we also called it as conventional milling.

Processing method of Tungsten Carbide End Mills – anticlockwise milling (up milling) and clockwise milling (down milling)

Characteristics of anticlockwise milling:

  1. Chip shape is from thin to thick, and cutter afford force from light into heavy, which may prevent the cutter fracture by the impact.
  2. Suitable for milling casting black surface.
  3. Can be used in the old milling machine, no screw invalid gap movement.
  4. More friction, the blade is easy to blunt, short life.
  5. Easy shaken, the machined surface is rough, poor machining accuracy.
  6. The device is not easy to settle, which is not suitable for milling thin parts.
  7. More energy consumption.

Clockwise milling:

The milling and feed in the same direction (milling with the feeds) called clockwise milling; Due to cutting action is from no-machining face of work piece into down place (chips from thick into thin), so it is called down milling or climb milling.

Processing method of Tungsten Carbide End Mills – anticlockwise milling (up milling) and clockwise milling (down milling)

Characteristics of climb milling:

  1. Chip is from thick into thin, cutter affords force from heavy into light, easy to cause fracture by impact.
  2. Not suitable for milling castings, forgings, and the surface of the work piece with fish scale shape.
  3. The milling machine shall have a gap eliminator, or easy to produce screw invalid gap movement.
  4. Processing less friction, longer life of the cutter edge.
  5. Easy chucking, no vibration, and high accuracy of the machined surface.
  6. The device is easy to settle, it’s suitable for milling long thin work pieces.
  7. Less feed consumption.
In most of the milling case, in addition to the casting of the first milling and old milling Lo-gap chopping device need to use the anticlockwise milling, down milling is better than conventional milling.

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Cutting Reference Data for End Mills of Various Materials

Effective working solution depends on correct cutters, operation method, and technology.

Usual cutting conditions and major influence factors of CNC machines.

  Introduction Formula
Cutting Data V(m/min) Cutting speed is decided by the diameter of end mills and its rpm V=Cutting speed(m/min)
D=diameter(mm)
N=rpm of one min of end mills(min-1)
Feed speed F(mm/min) Feed speed is the speed of relative one of work piece. Feed rate per flute is important for multi-flute end mills. F=Feed speed per minute
z= number of flute
f= Feed volume per flute
Cutting depth a(mm) Cutting depth is the thickness of flute machining on work piece. We always increase cutting depth to achieve its efficiency, but it is too deep to short tool life. It’s better to give proper cutting depth per flute, don’t increase feed rate and cutting depth together. -- --
Feed rate per flue
f(mm/刃)
Once a flute to cut -- --
Cutting width b(mm) Vibration caused by diameter of end mill, width of work piece, flute numbers, and cutting width. -- --

Cutting Speed

Work Material High Speed Steel Carbide – rough cutting Carbide – fine cutting
Cast iron (soft) 32 50-60 120-150
Cast iron (hard) 24 30-60 75-100
Malleable cast iron 24 30-75 50-100
Steel (soft) 27 30-75 150
Steel (hard) 15 25 30
Aluminum alloy 150 95-300 300-1200
Yellow Steel (soft) 60 240 180
Yellow Steel (hard) 50 150 300
Bronze 50 75-150 150-240
Copper 50 150-240 240-300
Hard Rubber 60 240 450
Fiber 40 140 200

Feed volume each side

Working Material Face cutter End Mill Spiral flute flat
end mill
Side Cutter Milling Cutter Metal gap cutter
HSS Carbide HSS Carbide HSS Carbide HSS Carbide HSS Carbide HSS Carbide
Cast Iron HB150-180 0.4 0.5 0.2 0.25 0.32 0.4 0.23 0.3 0.13 0.15 0.10 0.13
HB180-220 0.32 0.4 0.18 0.2 0.25 0.32 0.18 0.25 0.1 0.13 0.08 0.1
HB220-300 0.28 0.3 0.15 0.15 0.20 0.25 0.15 0.18 0.08 0.1 0.08 0.08
Malleable cast iron, Cast iron 0.3 0.35 0.15 0.18 0.25 0.28 0.18 0.2 0.1 0.13 0.08 0.1
Carbon steel Cutting steel 0.3 0.4 0.15 0.2 0.25 0.32 0.18 0.18 0.23 0.13 0.08 0.1
Soft steel, Steel 0.25 0.35 0.13 0.18 0.20 0.28 0.15 0.2 0.08 0.1 0.08 0.1
Alloy Steel Annealing robust steel HB180-220 0.20 0.35 0.10 0.18 0.18 0.28 0.13 020 0.08 0.1 0.05 0.1
HB220-300 0.15 0.3 0.08 0.15 0.13 0.25 0.10 0.18 0.05 0.10 0.05 0.08
HB300-400 0.10 0.25 0.05 0.13 0.08 0.2 0.08 0.15 0.05 0.08 0.03 0.08
Stainless steel 0.15 0.25 0.08 0.13 0.13 0.20 0.10 0.15 0.05 0.08 0.05 0.08
Al-Mg Alloy 0.55 0.5 0.28 0.25 0.45 040 0.32 0.30 0.18 0.15 0.13 0.13
Brass, Bronze speedy cutting 0.55 0.5 0.28 0.25 0.45 0.4 0.32 0.3 0.18 0.15 0.13 0.13
ordinary 0.35 0.30 0.18 0.15 0.28 0.25 0.20 0.18 0.10 0.10 0.10 0.18
hard 0.23 0.25 0.13 0.13 0.18 0.2 0.15 0.15 0.08 0.08 0.05 0.08
Coppper 0.30 030 0.15 0.15 0.25 0.23 0.18 0.18 0.10 0.10 0.08 0.08
Plastics 0.32 0.38 0.18 0.18 0.25 0.30 0.20 0.23 0.10 0.13 0.08 0.10

 

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The cutter materials and their contrast

This list includes eight cutter materials and their contrast as below:

  1. Mono Diamond)
  2. CO PCD
  3. Si PCD
  4. PCBN
  5. Si3N4
  6. SiC
  7. WC
  8. Steel
The cutter materials and their contrast
material Mono Diamond CO PCD si PCD PCBN Si3N4 SiC WC Steel
properties
Density g/cm3 3.52 3.8~4.10 3.4 4~4.20 3.2 3 15 7.8
Knoop Hadrness kg/mm2 6000~9000 5000~8000 5000 2700~3200 1800 2200 1500 560
Toughuess Mpam-2 3.4 6.1~8.9 6.9 4.1~7.2 6.4 4 11 46
Compression Strength Mpa 2000 7700 4200 3800 6800 7000 5400 1850
Tensile strength Mpa 2600 1300 600 500 470 400 1100 1760
Thermal Expansion 10-6/°C 0.8~4.8 1.5~3.8 3.8 3.5~4.2 3.5 3.8 4.3~5.6 11.2~14.3
Thermal Conductivity w/mk 600~1200 560 120 150 30 40 80 50
Friction   0.05~0.10 0.1 0.1 0.1 0.2 0.2 0.2 0.8

BW's popular products for tool series including circular saw, carbide cutting tool, saw blade, wood saw blade, special tool,side milling cutter, …etc; For machines we have spiral tube cooler, cutter grinder, and the latest design and advanced powder forming machine / pelletizer. Bewise is a superior manufacturer and supplier of cutter production and machinery industry.

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tool-How to choose the cutting tool for hardening material above HRC50?

There are higher requirements and more difficulties for many hardened molds. Hence general carbide cutters cannot reach such request of accuracy. Therefore, it should pay more attention to selection of cutting tools for hardened material.

Since hardening material which HRC is above 50, with higher hardness, the carbide cutter is difficult to meet the processing requirements, it will cause badly wear even break after CNC machining for about ten minutes. General carbide cutters cannot reach the request accuracy because the hardened mold is with higher requirement and difficulty.

Some points for choosing cutters for machining hardened materials as below:

  1. Select super micro grain carbide rod and design high rigid tool body to ensure toughness and rigidity of the tool.
  2. Select the blade the design of the large helix angle ranging from sub-and four-blade design so that the cutters may reach radial beating with heavy cutting within high-speed and high hardness cutting.
  3. Choose carbide cutter with new crystal coating. PVD coating almost cannot be used in high hardness cutting.. the crystal coating may solve it basically about the high temperature / acid resistance / wear / and longer tool life.
  4. Cooperate with the powerful tool companies to get their further technical supports and tool configuration, reducing the procurement chain and purchasing costs.

Good carbide cutters with high rigidity of the tool body and new type coating may get high efficiency, precision, and longer tool life. From pre-hardened steel to hardened steel, during high-speed, and high efficient processing; from rough to high precision machining, to achieve a long life; high precision; high quality processing makes it is easier to proceed high-speed and high rigid machining.

Article reference source : NewMaker

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Bewise Inc., being a professional manufacturer of various cutting tools, is endeavoring to make excellent products. We are very experienced in custom-made tools, and good at solving customers’ problems when they meet difficulties and troubles. Through everlasting research and practices, we understand thoroughly about different materials of cutters and cutting tools.

 

BW's popular products for tool series including circular saw, carbide cutting tool, saw blade, wood saw blade, special tool,side milling cutter, …etc; For machines we have spiral tube cooler, cutter grinder, and the latest design and advanced powder forming machine / pelletizer. Bewise is a superior manufacturer and supplier of cutter production and machinery industry.

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