TOO LS CU T B E TT ER WITH TIGRA

PCD FO R CU TTING TO O LS

2016

TO O L S CU T B E TTE R WITH TIG R A

INDEX Pages

1. Introduction

1

2. PCD - Basic information

1



2.1 About PCD manufacturing

1



2.2 Properties of different PCD compositions –



working on the edge

2.3 Application guide – select the best grade for your tool

2

3



2.3.1 Grain size and surface quality

3



2.3.2 Binder

4

3. Processing of PCD

4



3.1 Cutting

4



3.2 Brazing

5

4. Tooling cost

5

TO O L S CU T B E TTE R WITH TIG R A

1. INTRODUCTION Diamond, the hardest material known to mankind, has fascinated the world since its discovery. Created from carbon by the Earth under most extreme pressure and temperature conditions in thousands of years, diamond has become the most precious jewel found under the earth. It has been used for decades because of its beauty and only a short time ago man began to make use of the diamond‘s unique properties in the manufacturing of cutting tools and wear parts, thus creating a whole new industry for diamond. And even shorter back in time, we started to produce diamond and diamond-based compositions with high-end machines and equipment, aiming to repeat in hours what takes nature millions of years. These are used as the state-of-the-art cutting materials for aluminum, composites, woodbased board materials or also for wear protection. Creating the world‘s best diamond compositions through continuous research, testing and controlling has always been our goal and will continue to be the driving force for our future developments. With this guidebook, we want to help our customers to get an in-depth perspective on the manufacturing, composition and use of our polycrystalline diamond products, enabling you to manufacture an even better tool.

mixing of diamond powders and binders

high Pressure High Temperature pressing

2. PCD - BASIC INFORMATION 2.1 ABOUT PCD MANUFACTURING There are different methods for the artificial production of diamond and diamond-based compositions. It can be made either by the use of High Pressure High Temperature (HPHT) machines or by Chemical Vapour Disposition (CVD). There can be either pure diamond crystals or multiple ones, with binding materials or without. The products described here are all made by HPHT manufacturing. In this method, diamond grains are carefully selected for their size and mixed with binding agents. Together with a carbide disc as the base, they are put into a reaction cell which then is sealed and placed in a cubic press. The cubic press then equally applies pressure from all six sides of the reaction cell. This pressure of incredible 6 GPa is combined with heat of 1.800°C (3.272°F). During this process, the diamond grains inter-grow to a matrix with the binder still being embedded in it.

grinding

polishing

The binder later helps to both give stability to the cutting edge and enabling the product to be machined by electro-discharge machining (EDM). After this process, we receive a PCD disc (diamond substrate + binder on top, carbide on bottom) which needs to be ground and (mostly) polished to have a ready-to-sell product.

finished PCD discs

1

TO O L S CU T B E TTE R WITH TIG R A

2.2 PROPERTIES OF DIFFERENT PCD COMPOSITIONS – WORKING ON THE EDGE PCD typically comes in discs with a diamond- and a carbide side. While the tungsten carbide side is a typical tungsten + cobalt composition, making it easier to braze the diamond to the tool body, the diamond layer is more complex: Fine selected diamond grains are mixed in a matrix of binding agents. In the past, mostly cobalt was used for this. In modern PCD manufacturing technology, there is a mix of agents and binders which change the properties of the PCD substrate, making it more specialized for the application it is being used in. So there are three main factors that will have an influence on your cutting edge of your PCD tool: 1. diamond grain size 2. diamond content 3. binder composition In this chapter, we will have a more general look at these factors, detailing it in the next chapter. Diamond is extremely wear and abrasion resistant, making it an ideal cutting material. The lack of a substrate consisting of diamond grains is the toughness: PCD without binder would be very brittle. The binder makes the composition more tough and therefore suitable for many more applications. Just alike, the diamond grain size has high influence on the properties of PCD: smaller grain size gives higher stability as well as a sharper cutting edge (exception: laser finishing), but it has a lower abrasion resistance. There is an exception to all this: in recent development, ultra-fine PCD compositions have combined the properties of a great cutting edge quality, high stability and good abrasion resistance. Another important point to the tool manufacturer is the ease of making tools from PCD. Cutting and grinding have the greatest influence on tool cost so in many occasions, selecting an easy-to-work PCD grade is crucial to success.

As a general rule, we can sum up: - smaller grain size makes the PCD easier to cut and sharpen - higher binder content makes the PCD easier to cut and sharpen - TIGRA PCD grades use a specially composed carbide back for faster erosion

A combined explanation of the different TIGRA PCD types can be seen in Fig. 1 below. Name

Grain size (µm)

Grain structure

Binder type (µm)

0.5 - 0.8

standard

standard

FS

2-4

standard

standard

FX

2-4

special

reduced

MS

8-10

standard

standard

MX

8-10

special

reduced

MU

2-4 + 8-10

ultrahard

very high

CS

20-35

standard

standard

CX

20-35

special

reduced

CU

2-4 + 20-35

ultrahard

very high

standard

low

Fig. 1: Intercomparison of TIGRA PCD properties

Toughness (K1C)

Bending strength (TRS)

ES

GM60 8-10

2

Diamond content

Abrasion resistance

TO O L S CU T B E TTE R WITH TIG R A

2.3 APPLICATION GUIDE – SELECT THE BEST GRADE FOR YOUR TOOL In this chapter, we will try to give an overview of how to select the best grade for your tool. There are 4 decisive factors for tool makers when choosing the right grade to work on their cutting edge: 1. workpiece material 2. working conditions 3. desired workpiece surface roughness 4. cost The combination of grain size and binder will influence mechanical properties of the diamond and therefore your tool.

2.3.1 GRAIN SIZE AND SURFACE QUALITY The cutting edge of a diamond tool will depend on the method of cutting edge manufacturing as well as on the grain size of the diamond. Here, we will focus on EDM cutting edge manufacturing. Using electro-discharge, either by wire or wheel, is the most common used type of PCD tool manufacturing. Laser edge sharpening in contrary produces a mostly grain size independent, very sharp edge. Obviously, a finer diamond grain will lead to a sharper cutting edge, so the surface roughness is lowered. Fig. 2 shows the relation of the grain size to the surface quality.

Name

Roughing SemiFinishing SuperFinishing Finishing

ES

0

FS

0

FX

0

Al 12% Si GFRP

Woodbased boards

Comment

0

-

0

best finish

0

-

-

0

universal use, small grain

0

-

-

-

best for low Si%-Al

MS

0

0

0

MX

0

0

0

MU

0

universal use, medium grain

-

best for med. Si%-Al MDF, laminate

CS

0

-

0

CX

0

-

0

CU

0

-

0

universal use, coarse grain

0

best for high Si%-Al best for CFRP

GM60

wear parts, grindable

Fig. 2: Surface quality and tool life of TIGRA PCD

0 -

best performance good performance acceptable not suitable

3

TO O L S CU T B E TTE R WITH TIG R A

2.3.2 BINDER Binder type and quantity have great impact on the grade performance. With our three binding systems, there is the best choice for any application: “S” - Standard This pure Cobalt-binder is the basic of most of the different available PCD grades. It gives a strong bond to the diamond and at the same time helps to have a sharp cutting edge. Cobalt is a very good binder for universal applications. We recommend it for any general purpose grade and especially in wood-based materials “X” - special for aluminum and high-temperature machining While cobalt performs very well as a binder, it easily fails when the working temperature increases. Because of its thermal conductivity, it will not lead the heat away well from the cutting edge. Our special “X”-Binder is a multi-modular binder system with positive effects: - increased abrasion resistance - higher thermal conductivity - less built-up edges - very easy to cut and sharpen Like this, “X”-bound grades are the ideal choice for all aluminum machining applications. Higher tolerance on high silicate content as well as the better thermal conductivity make it superior to “S”-Standard grades there. On the other hand, we do not recommend “X” grades for wood-based materials. “U” Ultrahard: Any binder is softer than the diamond. Very abrasive workpiece materials such as CFRP always “wash out” the binder, removing it from the cutting edge and creating surface roughness and tool failure. In highly abrasive materials like many composites, the only way to obtain good tool life is by a very sharp cutting edge. This can be reached by using PCD grades with very low binder content. In addition, we replaced some of the cobalt binder with tungsten, being harder and more abrasion resistant than cobalt. In CFRP and GFRP as well as laminate flooring and medium to hard density fibreboard, “U”- binders are the best choice for your tool.

3. PROCESSING OF PCD 3.1 CUTTING Cutting of PCD blanks by wire

PCD by TIGRA is available in 2 versions: In round discs with various total and PCD layer thicknesses as well as in cut-to-size pieces, both with and without angles. Today, most of the tool manufacturers buy cut-to-size segments for large volumes and discs for smaller volumes. The two common ways of disc cutting are by wire EDM and by laser. TIGRA is using both technologies, with laser used mainly because of the lower overall cost. General recommendations for laser cutting cannot be provided since there are too many different laser technologies. When cutting by wire, please make sure that • water temperature is between 18-25°C (25-77°F). • cut pieces are removed from water as quickly as possible. • there is plenty of de-ionised water. • damage zone of cut pieces is calculated in the shape (around 0.04 mm for wire cut and 0.05 mm for laser-cut pieces).

PCD laser cutting

4

TO O L S CU T B E TTE R WITH TIG R A

3.2 BRAZING Diamond graphitizes with temperatures exceeding 730°C (1346°F). Also, a long brazing time at higher temperatures damages the diamond. The (carbide) brazing side of the PCD segments oxydates when stored for a longer time or at elevated humidity. For a good braze (mainly induction brazing is used), please make sure that • segments are sandblasted before brazing if stored (TIGRA supplies tips sandblasted). • both segment and seat are clean. • flux and brazing alloy are good for temperatures around 670°C / 1238°F. • brazing time is kept as short as possible. • cooling of tool is on air or in silicate, long time, in non-cooled place.

Special recommendations for sandwich PCD • measure the thickness of each cut PCD segment • use tungsten carbide as tool body material • wire-cut the seat pocket in the tool body • make a small undercut/relief cut at the bottom of the seat pocket corners • tolerance of the seat pocket: segment thickness +0.15 / +0.1mm (+.006/+.004 inch) • shortly sand blast and wash the seat pocket • keep brazing time as short as possible

Brazed PCD segment on a reversible knife

3. TOOLING COST

Total cost

In a competitive market, our customers are not only trying to make the best, but also a reasonably-priced cutting tool. Depending on the type of tool, diamond and machining time can have a high impact on the finished tool’s cost. By supplying PCD tips with a higher electrical conductivity, TIGRA has already increased cutting and finishing speeds around the world. In comparison to many other standard grades available on the cost cost market TIGRA´s PCD segments using our “S”-grades and “X”-binder 100% 86% 100% can be processed around 20% faster. Total cost Furthermore, cut segments with an angle will save additional time in saving 14% finishing equalling around 20% with a 25° clearance angle. EDM grinding EDM grinding time 35% time 21% On a typical PCD saw blade, where grinding time is a high cost factor, finally up to 40% of the grinding time cost (14% of the total cost) can PCD PCD be saved using a medium-grain size PCD with increased conductivity 30% 30% (e.g. “MS”) and a 20-25% clearance angle on the cut tip.

Other cost 35%

A

Other cost 35%

PCD versions

B

A: PCD market example

B: TIGRA

less conductive tip without clearance angle

MS grade with clearance angle

Fig. 3: Savings on a PCD Saw Blade cost, MS grade, precut angle

5

TO O LS CU T BET TER WITH TIGRA

www.tigra.de

TIGRA GmbH Gewerbering 2 D-86698 Oberndorf am Lech · Germany Phone +49 (0)9090 9680-01 · Fax +49 (0)9090 9680-50 www.tigra.de · [email protected]

1106 8th ST CT SE Hickory, NC 28602 · USA Phone +1 828-324-8227 · Fax +1 828-324-8097 www.tigra-usa.com · [email protected]

TIGRA do Brasil Ltda. Rua das Carmelitas 586 · Hauer 81610-070 Curitiba-Paraná · Brazil Phone +55 41 3276 3731 · Fax +55 41 3377 3075 www.tigradobrasil.com.br · [email protected]

TIGRA China Co. Ltd. 1-1-101 Hua Long Mei Shu · No.15 Jian Guo Road ChaoYang District · Beijing, 100024 · P.R. China Phone +86 10 5921 4353 · Fax +86 10 5921 4352 www.tigra-china.com · [email protected]

© TIGRA GmbH 2016 We reserve the right to make technical changes for product improvements.

TIGRA USA, Inc.