parts and more compact picks - wirtgen...

www.wirtgen-group.comROAD AND MINERAL TECHNOLOGIES

PARTS AND MORE COMPACTPICKS

CONTENTS

2 I 3

ADVANTAGES PAGE 4

ORIGINAL WIRTGEN PICKS PAGE 4

On the meaning of GENERATION X Page 5

Quality tools Page 6

FACTS PAGE 8

The components of a pick Page 8

The carbide tip Page 10

The brazing Page 18

The steel body Page 20

The wear plate Page 22

The clamping sleeve Page 26

APPLICATION PAGE 28

Pick and toolholder system optimisation Page 28

Wear of picks 0

Optimum wear Page 32

Cutting length and chip volume Page 36

Milling depth and wear Page 40

Wear patterns (optimum) Page 42

Selection tables Page 45

Wear patterns (undesirable) Page 50

System comparison Twin-Head Page 56

ADVANTAGES | FACTS | APPLICATION

You can’t do without them

Picks have played a decisive role in Wirtgen’s milling tech-nology for more than 50 years. During the milling pro-cess they loosen the pave-ment and granulate it into small pieces of reusable ma-terial. The wide variety of conditions and load cases dealt with in everyday opera-tion on the job site demand and promote continuous pick development.

Optimised Wirtgen

cutting technology

Based on information and data collected in practice it can be seen that for cold milling, in particular, produc-

tivity and economic aspects are becoming increasingly rel-evant. In addition to increasing the pick service life, the focus is on increasing machine productivity in particular, and mini-mising the ensuing operating costs. In terms of these de-mands, Wirtgen cutting technology has been fundamentally optimised in its GENERATION X range.

Pick

ORIGINAL WIRTGEN PICKS

4 I 5

High efficiency pays off

Economic efficiency, defined as the ratio of success achieved to the invested means, is dependent on numerous factors, even for complex construction machinery. For Wirtgen, the cutting technology, and especially the pick, is of central im-portance. The formula “A low pick price results in greater eco-nomic efficiency” does not work here. It depends on the cor-rect interaction of pick and machine. The pick type and the geometry must be matched to the machine’s task.

Features of GENERATION X can be found in all Wirtgen cutting technology components: Pick wear plate Cap-shaped pick tips

This brochure gives you the opportunity to familiarise your-self with the wide variety of Wirtgen road milling, recycler and stabilizing picks, and to find the most economical alternative for any given site situation.

Enhance your knowledge of Wirtgen cutting technology with regard to milling and find out more about the new, advanced GENERATION X pick.


Competent partnership

When construction machine and tool manufacturers pool their expertise, this has many benefits for you as the customer.

Wirtgen and BETEK developed the first road milling pick in co-operation in 1983. Since then, both companies have utilised their experience to continuously develop the pick. The head office of BETEK Bergbau- und Hartmetalltechnik is located in Aichhalden in the Black Forest and forms part of the SIMON

QUALITY TOOLS FOR HIGH-PERFORMANCE MILLING MACHINES

Sintering the carbide tips at extremely high temperatures

6 I 7

group of companies founded in 1918. The close cooperation of the system partners Wirtgen and BETEK enables us to quickly react to our customers’ wishes and suggestions. Development, design and production of a wide range of cutting tools at BETEK, perfectly matched to the different machine types of Wirtgen, ensure the maximum performance capability of both machine and pick in service.

This close cooperation shows:

Due to their individual design, picks are not classical bought-in parts. Only in combination with the corresponding, highly spe-cialised Wirtgen machines can this regularly give the optimum milling result with maximum productivity.

Summary: The combination of both these areas of expertise forms the basis for the best possible service and greatest economy of your machines in daily use.

1

2

3

4

5


THE COMPONENTS OF A PICK

8 I 9

Picks for road milling machines, recyclers and stabilizers

usually consist of five components:

1 Carbide tip

2 Brazing

3 Steel body

4 Wear plate

5 Clamping sleeve

The design varies between the different types of picks, as they are intended for a very wide range of applications. The compo-nents and their function, however, are always identical.

Road milling pick W7/20X

Stabilizing pick W1-17/22


THE CARBIDE TIP – TUNGSTEN CARBIDE AND COBALT WITH A PERFECT BOND

The carbide in our tips is a composite material made from tungsten carbide and cobalt. While the tungsten carbide pro-vides extreme hardness and resistance to wear, the compara-tively “soft” cobalt bonds the tungsten carbide particles to ensure maximum breaking strength under even the greatest stresses.

1 Carbide under the microscope

2 Cobalt bonds with the tungsten carbide grains and provides im-pact resistance.

3 Tungsten carbide is very hard, and provides the wear resistance, with a proportion of weight by ap-prox. 94 %

1

10 I 11

2 3

The balanced mixture of different particle sizes of the tung-sten carbide largely determines the wear of the tips. The fine particles ensure high wear resistance, while the coarse parti-cles provide the necessary breaking strength and temperature resistance. The incorrect mixing ratio of coarse and fine parti-cles causes increased wear in the high-temperature cutting process, which results in premature failure of the tool.

Stringent quality controls at BETEK ensure the consistent and correct mixing ratio.

Summary: The quality of the carbide determines the service life of the pick, and consequently also the machine avail-ability, its milling performance and the quality of your site operations.


Cylindrical carbide tipCap-shaped carbide tip Precursor model

GENERATION X W6

THE PICK TIP – GEOMETRICAL OPTIMISATION WITH GENERATION X

12 I 13

All cap-shaped carbide tips have been remodelled to suit

the requirements of GENERATION X. The aim is to increase carbide utilisation and further optimise the pick’s service life. This is achieved by displacing the carbide to the upper region of the abrasion-relevant areas.

A comparison of carbide tips (left) shows that GENERATION X displays a highly cylindrical component in the upper region of the tip. This design primarily optimises the cutting perfor-mance, leads to constant machine productivity, improves the cost-performance ratio and enhances the pick’s service life.The m³ performance per cutting tool is also increased.

Picks with cylindrical carbide tips are classified as GENERATION X if they are equipped with the typical wear plate (see pages 22 to 25).

4.85

4.85


THE PICK TIP – ENHANCING THE SERVICE LIFEOF GENERATION X

A direct comparison between the carbide tips of

GENERATION X and those of our precursor models demon-

strates the principal differences at a glance (see figure at top). The total wear margin of both carbide tips is 9.7 mm.However, if we compare them at 50 % of the wear margin, ap-prox. 4.85 mm, it is clear that 16.9 % more carbide remains in the upper section in the case of the GENERATION X W6 tip than on the precursor model, even though the carbide tip weight is identical in each case.This greater volume hinders lengthwise wear and the service life of the pick is increased (cf. Table on page 16).

GENERATION X W6

Wear margin of a W6 carbide tip for comparison:

Precursor model and GENERATION X

Cap-shaped carbide tip W6 Precursor model

5

0

10

15

20

25

50 500 1500 2000 2500Milling distance in metres

14 I 15

Mac

hine

adv

ance

m/m

in

Practice tests emphasise the advantages of GENERATION X, pointing out that the optimised carbide tip geometry com-bines the reduced cutting forces of a cylindrical tip with the protection function of the cap-shaped carbide.The excellent cutting performance over approx. 3/4 of the car-bide tip’s service life (see figure above: Precursor model and GENERATION X in comparison) results in the high machine ad-vance rate and productivity.

In summary: The GENERATION X carbide tip allows maximum carbide utilisation and the longest possible pick service life.

Precursor model, size W6 Generation X, size W6

Machine advance rate in comparison:

Precursor model and GENERATION X


THE PICK TIP –CARBIDE COMPARED TO GENERATION X

Percentage, type-dependent carbide redistribution

W4-G/20X with +18.5 % W4-G/20X with +18.3 %

Pick precursor products compared to GENERATION X

GENERATION X Precursor products Carbide redistribu-tion in %Part No. Designation Part No. Designation

Without extractor groove

2314701 W5L/20X 2218477 W5/20 29.9

2308098 W6/20X 2218478 W6/20 16.9

2308100 W6M/20X 2218486 W6M/20 ---

2308102 W7/20X 2152111 W7/20 18.3

2308104 W8/20X 2218482 W8M/20 16

With extractor groove

2308094 W4-G/20X 2218469 W4-G/20 18.5

2308097 W5L-G/20X 2261899 W5-G/20 29.9

2308099 W6-G/20X 2218471 W6-G/20 16.9

2308101 W6M-G/20X no precursor product ---

2308103 W7-G/20X 2218473 W7-G/20 18.3

2308105 W8-G/20X 2218474 W8M-G/20 16

1817.5

Ø 11.5Ø 10.5

Ø 19Ø 19

16 I 17

The difference between the GENERATION X carbide tips

and the corresponding M tip design (M for massive) pre-

dominantly lies in the volume of carbide used. Thanks to the greater carbide use in the lower section (also comparing the carbide weight on the tips, see above), and in the upper tip section with its larger diameter, the M version is even more resistant and fracture proof than the normal GENERATION X tips.

Carbide volume compared to GENERATION X M tip

W6/20 GENERATION X, 30.2 g W6M/20 GENERATION X, 36.4 g


THE BRAZING – RELIABLE HOLD OF THE CARBIDE TIP ON THE STEEL BODY

The carbide tips are brazed firmly to the steel body. As soon as the enormously high temperatures generated during the milling process act on the components, the carbide in the tip and the steel of the pick head are subject to differential ex-pansion. A brazing method developed in-house is used, which under the effect of heat ultimately determines the hardness of the pick head.

This is confirmed by numerous stress tests: Even under enor-mous pick stresses, no breakage occurs. The carbide tip and steel body hold firmly together.

The brazing

Summary: The careful brazing of the tungsten carbide tip and the steel body ensure the firm bond of the materials.

18 I 19

Using a specially confi gured device, test picks are removed from current pro-duction in order to test the durability of the braze for quality control purposes.


THE STEEL BODY – HARD AT THE TOP AND TOUGH AT THE BOTTOM

The pick head must withstand enormous shear forces and impact stresses. At the same time, the pick must sit firmly and unbreakably in the toolholder throughout its complete service life. Wirtgen picks have a steel body which perfectly combines the two properties of wear resistance and breaking strength.

In a tried and tested process different grades of pick head and shaft hardness are produced: While the tough pick shaft ab-sorbs the forces occurring in the area of the toolholder, the pick head undergoes extra hardening, making it particularly wear-resistant in direct contact with the milling material.

Put to the test: A 300 kg weight hits the pick from a height of 1.5 m

20 I 21

Summary: The relationship of hardness to toughness of the pick head and shaft largely determines the service life and usability of the pick.

1.55

2.25


THE WEAR PLATE – OPTIMISED FOR GENERATION X

Precursor model and GENERATION X wear plate

Precursor model wear plate

GENERATION X wear plate

22 I 23

Wear protection

The design of the wear plate plays a crucial role for the wear state of the toolholder. Wirtgen picks are therefore provided with a wear plate with an outer plate diameter of 45 mm, ex-actly matched to the toolholder. It completely covers the upper part of the toolholder and thus absorbs a large proportion of the wear and tear. Wirtgen picks are optimised on the basis of requirements and experience gathered on site. The forged wear plate has a pronounced chamfer on the underside, which was increased once more in the GENERATION X (see left figure).This chamfer transfers the shear forces generated during the cutting process far better. In addition to the improved pick cen-tring, these shear forces are effectively transferred to the tool-holder system.

The installation aid

In the delivery condition, the clamping sleeve of the pick is pre-tensioned by the wear plate. Therefore, only a few operations are required to install the pick ready for use.


THE WEAR PLATE – LARGE CONTACT SURFACE FOR GENERATION X

The contact surface of the chamfer to the toolholder was

increased from 47.3 mm2 to 114.5 mm2 in GENERATION X (surface increased by more than 140 %). The shear forces generated during the cutting process are therefore more ef-fectively transferred.

Cone contact area on the under-side of the wear plate corresponds to 47.3 mm²

Cone contact area on the under-side of the wear plate corresponds to 114.5 mm2, therefore +140 %

24 I 25

Shear forces generated during cutting process

The rotary movement of the pick required to achieve optimum (radial) wear and the shear forces (tipping movement) gener-ated during the cutting process allow milled material particles to penetrate into the gap between the toolholder and the wear plate, depending on the respective application. For example, asphalt particles promote lengthwise wear on the toolholder as a result of their abrasive properties.Thanks to the extremely pronounced cone on the underside of the GENERATION X wear plate (increased by 140 %, also see left-hand figure), the tipping movement is greatly reduced. This means that less dirt particles penetrate into the gap (be-tween the wear plate and the toolholder contact area). How-ever, in addition to the reduced risk of pick fracture, primarily the toolholder service life is significantly increased in terms of lengthwise wear.

In summary: In addition to their other properties the GENERATION X wear plates reduce lengthwise toolholder wear.

Heavily worn toolholders as a result of the massive penetra-tion of dirt caused by the tip-

ping movement during the cutting process. Cause: Picks

with an excessively small cone on the underside of the wear

plate were used.


1

THE CLAMPING SLEEVE – STRONG HOLD AND QUICK REPLACEMENT

Thanks to its exact roundness, the Twin-Stop clamping

sleeve ensures optimum pick rotation characteristics.

The Twin-Stop function with an upper and lower stop collar enables the clearly defined lengthwise play of the pick under the changing stresses during the cutting process. This dra-matically reduces the risk of damage to the sleeves and/or the number of pick breakages.

The clamping sleeve for the current range of picks has a wall thickness of 1.25 mm and has therefore been reinforced throughout. This optimization significantly extends the pos-sible use of the shaft-sleeve joint.

The comparatively high hardness of the clamping sleeve en-sures a high clamping force, which counteracts premature

1 The Twin-Stop clamping sleeve with improved rota-tion characteristics

2 Conventional clamping sleeve with an axial stop in the unprotected area

3 Twin-Stop stops in the protected area for re-duced wear

failure in even the most demanding applications. A special surface treatment protects the sleeve against corrosion and therefore ensures straightforward pick removal.

26 I 27

2 3

Summary: The holding force is great enough to guaran-tee a reliable milling process in every situation, and simultaneously low enough to allow uncomplicated and quick pick replacement.


PICK AND TOOLHOLDER SYSTEM OPTIMISATION

During further development, or better redevelopment, of

the HT22 quick-change toolholder system, optimisation

of the service life of the system as a whole as well as of

the upper part of the toolholder played a central role. The revised design of the Wirtgen pick is therefore required in or-der to enhance this improvement as far as possible.The result is the improved design of a thicker wear plate and an improvement in the material flow around the carbide tip and the pick head. The primary feature is the cone on the un-

28 I 29

derside of the wear plate, which was adapted to the upper part of the toolholder (also see pages 22 to 25).

In the combination of HT22 toolholder system and GENERATION X picks, in particular, service life achieves ideal values and exceeds the properties of the individual compo-nents. Using these two new Wirtgen developments, machine availability is greater than for any other combination.Finally, this general optimisation of Wirtgen cutting compo-nents leads to increased productivity, setting new standards.

Find out more about this progressive quick-change tool-holder system in the brochure Parts and More Compact –

HT22 Quick-change Toolholder System.


WEAR OF PICKS – REASONS AND TIPS FOR MAINTENANCE

All elements of a pick are subject to more or less wear de-pending on the material to be milled. In case of excessive fa-tigue on one of the components, e.g. the carbide tip, the steel body, the wear plate and/or the clamping sleeve, the pick should be replaced to prevent or reduce consequential dam-age to the more expensive toolholder system, which is also more complex to replace.

Dirt, incorrect installation or elements from different manufac-turers that are not identical will degrade not only the produc-tivity and/or the milling performance, but can even result in irreparable damage to the entire milling drum.

The most common reasons for unusually short pick service

lives include:

Coatings and accumulations of old milled material, generally from ineffective cleaning. Selection of the wrong pick (see usage recommendations,

pages 45 to 48) Inadequate supply of water by the sprinkler system in the

milling drum housing

What is wear?

Wear is produced by two elements pressing against each oth-er with relative movement (for example between carbide tip and the material to be milled). During this process small parti-cles become detached from the surfaces of both elements.

30 I 31

How can wear be avoided?

Wear on picks cannot be prevented entirely, but at best minimized.An adequate water supply is an important basic prerequisite to ensure the necessary rotation of the picks. The selection of the correct pick (depending on the substrate to be milled) also optimizes the use and reduces the wear.

Increasing service life means

paying attention to thorough, daily cleaning, regularly inspecting the picks so that wear or damage to

components can be tackled in good time, regularly maintaining and checking the sprinkler system and selecting the cutting tools to suit the application.

Correct installation of the picks

Check the amount of dirt and the possible need for cleaning of the toolholder bore prior to the actual installation. Usage of appropriate tools to prevent damage to the

carbide tip (copper hammer or pneumatic insertion tool). Manual inspection of the pick rotation

(turning the pick by hand).


The correct assessment of the wear to Wirtgen picks is

an essential requirement for smooth and efficient project

handling. Replacing a pick at the right time guarantees suc-cessful working, and ultimately also reduces operating costs significantly. Using the measured lengthwise wear on picks with a cap-shaped carbide tip (check dimension “B”), conclu-sions on the penetration capacity of the pick in the material to be milled can be drawn. The more advanced the wear (the overall length of the pick decreases, compare dimension “A” to “B”), the lower is the penetration capacity. In addition to a reduced machine advance rate, this effect is reflected in sub-stantially lower productivity.

Numerous influencing factors must be taken into consid-

eration when assessing the condition of picks: from cli-matic conditions through milled material, machine perfor-mance and machine advance speed to proper maintenance. Wear patterns and observation of the maximum wear lengths help to avoid missing the correct replacement time, and pre-vent typical errors in applications.

THE OPTIMUM WEAR OF THE PICKS

BC

A

32 I 33

Pick new Pick worn out


THE OPTIMUM WEAR OF THE PICKS

Designation Part No. Pick new (A)

Pick usage for road milling machines

W1-8/13 193701 54.2 mm

W1-10-G/20X 2218466 88 mm

W1-13-G/20X 2281964 88 mm

W4/13 182598 54.2 mm

W4-G/20X 2308094 88 mm

W5L/20X 2314701 89.5 mm

W5L-G/20X 2308097 89.5 mm

W6/20X 2308098 88 mm

W6-G/20X 2308099 88 mm

W6M/20X 2308100 88.6 mm

W6M-G/20X 2308101 88.6 mm

W7/20X 2308102 88 mm

W7-G/20X 2308103 88 mm

W8/20X 2308104 88 mm

W8-G/20X 2308105 88 mm

Pick usage for recyclers and stabilizers

W6/22 2064872 91 mm

W6-T/22 2143715 91.5 mm

W8M/22 2088117 91 mm

W8M-T/22 2143717 91.5 mm

W1-13/22 2088111 91 mm

W1-17/22 2088112 91 mm

W6-C/22 2064870 83.5 mm

34 I 35

Pick worn out (B) Wear path (C)

43.6 mm 10.6 mm

68.2 mm 19.8 mm

69.8 mm 18.2 mm

44.5 mm 9.7 mm

78.3 mm 9.7 mm

79.8 mm 9.7 mm

79.8 mm 9.7 mm

78.3 mm 9.7 mm

78.3 mm 9.7 mm

78.2 mm 10.4 mm

78.2 mm 10.4 mm

75.9 mm 12.1 mm

75.9 mm 12.1 mm

75.2 mm 12.8 mm

75.2 mm 12.8 mm

81.3 mm 9.7 mm

81.8 mm 9.7 mm

79.9 mm 11.1 mm

80.4 mm 11.1 mm

72.8 mm 18.2 mm

74 mm 17 mm

81.3 mm 2.2 mm


CUTTING LENGTH AND CHIP VOLUME

In the three functional examples given the same milling

drum type is used. The diameter of the cutting circle is 1140 mm, the milling drum operating speed is 98 1/min. As can be seen in the illustrations and data, the maximum ad-vance (V) of the road milling machine reduces with increasing cutting depth (A) (see pages 38 to 39).

Explanation:

In example 1 the cutting depth is 50 mm. Referred to the cir-cumference of the milling drum the percentage of picks in contact is 11 %. An advance performance of can 30 m/min is achieved.For comparison the cutting depth in the third example is 300 mm. 18 % of the milling drum circumference is in the cut, which has the consequence that the engine power applied is distributed over a greater number of picks and as a result the machine advance is reduced.

Given constant ambient conditions (machine, milling material, pick type, etc.) the milling depth (A) has a direct effect on the advance of the machine. Accordingly, the volume of comma-shaped chips milled also changes as a function of the ma-chine parameters described above. The maximum milling ma-terial volume performance is achieved at a medium milling depth.

AA

A

v

v

v

36 I 37

Example 1

Example 2

Example 3

AA

B

B


CUTTING LENGTH AND CHIP VOLUME

Example 1

Example 2

Cutting process

Milling depth (A)

Remaining web height (B)

Rotations per minute

Example 1 50 mm 18.56 mm ca. 98 1/min



A

B

38 I 39

The relationship between cutting depth and advance per-

formance can also be read from the resulting chip length.

The deeper the cut, the longer the contact friction with the compacted substrate lasts. The duration of the friction results in higher wear.

Example 3

Advanced Speed

Total circum-ference of the milling drum

Length of the contact friction (circumference in cutting process)

ca. 30 m/min ca. 3700 mm ca. 408 mm (11 %)

ca. 10 m/min ca. 3700 mm ca. 474 mm (14 %)

ca. 5 m/min ca. 3700 mm ca. 632 mm (18 %)

Mill

ing

dept

h in

mm

125

275

150

300

100

250

75

225

50

200

100

50

200

100

300

150

400

200

500

250

600

300

350

25

175

325

Travel of the pick per cut in mm

Theoretical milling volume in m³/h


MILLING DEPTH AND RESULTING WEAR TO PICKS

In addition to the material in question, the most impor-

tant influencing factors for the milling performance are

the milling depth and the machine advance speed.

Travel of the pick per cut in mm Theoretical milling volume (milled material) in m³/h Region with highest milled material volume and

theoretical minimum comparison

40 I 41

Summary and practical tip: In some applications, the re-quired milling depth is greater than 200 mm; in this case, it may be well worthwhile to remove the layers in several operations (cuts), since the advance per cut is increased and the wear to the picks per cubic metre can be reduced.

A major but often overlooked detail: At different milling depths, the cutting profile of the pick and therefore the chip size of the milled material differ significantly (also see exam-ples pages 37 to 39).

This has a direct effect on the milling performance and the wear to picks and toolholders. Wirtgen large milling machines produce the maximum milling performance and lowest wear costs at a milling depth of from 75 mm to 150 mm.

It can therefore be said in summary that the maximum

economy can be achieved at these milling depths.


THE OPTIMUM WEAR TO THE PICKS – WEAR PATTERNS

Picks with a cap-shaped carbide tip

This shows an example of an ideally worn pick. This can be seen from the carbide tip worn to the maximum and the even radial wear to the pick head.


Picks with a cylindrical carbide tip

The figure shows an optimally worn pick with optimum rota-tion; however, the length is not yet completely worn.

Picks with a cylindrical carbide tip can be used until they reach the wear marking above the wear plate (see notch on pick head). When the marking is reached the carbide is worn to its maximum.

42 I 43

Picks with a cap-shaped carbide tip and chamfered wear plate

This result is almost ideal, since here too the pick shows ra-dial wear, as in the previous example. In the further milling process, the operator should keep an eye on the condition of the already very chamfered wear plate, because if it becomes too severely worn, it no longer protects the toolholder prop-erly against wear to its contact surface.

PICK RECOMMENDATION FOR ROAD MILLING MACHINES, COLD RECYCLERS AND STABILIZERS

• • Generally recommendable • Recommendable

Pick recommendation for recyclers and pulverizers

Material property

St

Shaft diameter 22 mm (Standard version for

Designation W6-T/22 W8M-T/22

Part No. 2143715 2143717

WR 2000, WR 4200 • • •WR 2400, WR 240, WR 2500, WR 2500 S • • •

Pick recommendation for road milling machines – Selection prog

Material to be milled

Carbide tip diameter

Pick load classes

Head design

Designation

Part No.

1 0.35 m W 350, W 350 E, W 35, W 35 DC

2 0.5 m W 500, W 50, W 50 DC

3 1m (Rear) W 600 DC, W 1000, W 60, W 100, W 1000 L

4 1m (Front) W 1000 F, W 1200 F, W 1300 F, W 100F, W 120 F, W 13

5 2 m Mid-range W 130, W 150, W 1500, W 1900, W 200, W 2000

6 2 m Top-range W 210, 2100 DC, W 2100, W 2200, W 250

Partly recommendable

Impact stress (material hardness) increases

eel body wear (fine component in material) increases

Wirtgen recyclers and pulverizers)

W6/22 W8M/22 W1-13/22 W1-17/22

2064872 2088117 2088111 2088112

• • • • • •• • • • • • •

gramme

Asphalt (cap-shaped carbide tips)

W4 W5 W6

Without ex-tractor groove





W4/13 W4-G/20X W5L/20X W5L-G/20X W6/20X

182598 2308094 2314701 2308097 2308098

• • • •• • • • •

• • • • • •30 F • • • •

•

45 I 48

Concrete (cylindrical carbide tips)

W8 W1






W8/20X W8-G/20X W1-8/13 W1-10-G/20X W1-13-G/20X

2308104 2308105 193701 2218466 2281964

• • •• •• •• • •• • •

• • • • •

Impact stress (broken stone component) increases

l body wear (fine component in material) increases

irtgen stabilizers)

π W6C/22 W1-13/22 W1-17/22

2064870 2088111 2088112

• • • • • • • • • •• • • • •

W6M W7





With extractor groove t

W6-G/20X W6M/20X W6M-G/20X W7/20X W7-G/20X

2308099 2308100 2308101 2308102 2308103

•• • • •• • • • • • •

• • • • •

Material recommendation for stabilizers

Material propertyI

Steel

Shaft diameter 22 mm (Standard version for Wi

Designation W6/22 W8M/22π

Part No. 2064872 2088117

WR 2000, WR 4200, RACO 350 • • •WR 2400, WR 240, WR 2500, WR 2500 S • • WS 2000, WS 2500, WS 220, WS 250 • • •


Carbide breakage

Condition:Figures 2 and 3 show a carbide tip after breakage due to overload.

Cause:There are basically two causes of a carbide breakage: Firstly, a mechanical overload may occur, if the ground

being milled contains hard objects or materials which cannot be cut or broken, such as steel reinforcements, large rocks or drainage covers. Secondly, a thermal overload may be caused by excessive

heat generated in the cutting process. This occurs in case of inadequate water supply in the cut of the pick.

2

44 I 49

1

UNDESIRED WEAR – WEAR PATTERNS

Picks with a cap-shaped carbide tip

Condition:Good general condition of the pick with the exception of the wear plate. The diameter is too heavily worn and offers the toolholder insufficient protection. The steel body (with tip) however is only one-third worn. The pick indicates optimum rotation characteristics.

Solution:By selecting a smaller carbide tip, in this application it might be possible to simultaneously achieve equally high utilisation of the carbide tip, the steel body and the wear plate.

50 I 51

Solution: Damage due to mechanical overload is difficult to avoid,

since steel reinforcements or large rocks in the substrate cannot be detected before the start of milling. In order to prevent a thermal overload, the sprinkler system

(water pump, sprinkler bar and its components, such as nozzles and filters) should be checked.A further possibility is to reduce the advance speed of the machine, since this, together with the drum speed, determines the cutting length of the picks. The longer the cutting length, the greater the friction created. This ultimately also leads to overheating of the picks.

3



Steel body washing out

Condition:The steel body and wear plate are already severely worn in comparison to the carbide tip. The pick demonstrates optimum rotation.

Cause:One possible cause for this form of wear is a high advance speed with soft milling material. These conditions usually lead to washing out at the pick head and reduced wear to the car-bide tip.

Solution:There are two means of minimizing this undesired wear: Using a pick with a larger steel body or carbide diameter Reduction of the machine advance speed or machine speed

52 I 53

Excessive lengthwise wear

Condition:The pick is completely worn. It has exceeded its maxi-mum service life, since there is no carbide left to be seen. The toolholder has probable been severely damaged at the contact surface, since it is not protected either by a wear plate or a pick head.

Cause:The pick wore out long ago, and was detected much too late.

Solution:In order not to exceed the optimum replacement time, regular checks should be carried out during occasional breaks in the milling process.



Clamping sleeve wear

Condition:The figure shows a classical clamping sleeve, which has be-come deformed due to its design (without twin-stop function) after being used for too long.

Cause:This pick had been in use for a very long time. Even if this can-not be seen from the pick head and the carbide tip, it can al-ways be identified from the wear of the wear plate and clamp-ing sleeve.

Solution:For the general reduction of this risk, the Twin-Stop function (with exactly defined lengthwise play) was integrated into Wirtgen picks. New GENERATION X features additionally reduce this risk.

54 I 55

Bad rotation

Condition:On this pick with a cylindrical carbide tip, severe wear can be seen to one side of the pick head and the carbide tip. This is most probably due to inadequate rotation characteristics.

Cause:One reason for failure can be dirt in the toolholder bore. This occurs in the event of inadequate water supply. A further cause for the bad rotation characteristics can be a severely abraded toolholder.

Solution:First, the general condition of the water system should be checked. It must also be ensured after dismantling the pick that the toolholder bore is cleaned, and that the toolholder contact surface is not worn on one side.

1


System comparison with steel washing out

Condition:The example shown (Figure 1) is one of the Twin-Head pick gener ation with a 22 mm shaft diameter, which is equipped with an extremely resistant wear cone.

SYSTEM COMPARISON FOR THE TWIN-HEAD PICK GENERATION WITH 22 MM SHAFT DIAMETER

2

56 I 57

In contrast to the earlier type, this pick is not prone to washing out under the carbide tip, as is indicated in Figure 2. Better holder protection is also provided, since in this case the wear cone can still protect the toolholder after extensive use in comparison to standard picks.

WIRTGEN GMBHReinhard-Wirtgen-Strasse 253578 Windhagen · Germany

Phone: +49 (0) 26 45/131-0Fax: +49 (0) 26 45/131-397

E-mail: [email protected]

JOSEPH VÖGELE AGJoseph-Vögele-Strasse 167075 Ludwigshafen · Germany

Phone: +49 (0) 621/8105-0Fax: +49 (0) 621/8105-463


HAMM AGHammstrasse 195643 Tirschenreuth · Germany

Phone: +49 (0) 9631/80-0Fax: +49 (0) 9631/80-120


KLEEMANN GMBHManfred-Wörner-Strasse 16073037 Göppingen · Germany

Phone: +49 (0) 7161/206-0Fax: +49 (0) 7161/206-100

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