Work parameters

Cutting speed, pass depth and travel speed are the most important parameters for all types of machining; indications for the ideal values will be given with reference to the specific tasks.
From a general point of view, it has to be remembered that the exact setting of the right cutting speed is one of the most important things to do when working with titanium, because if speed exceeds even by just a little the correct value, it will greatly reduce the tool`s working life.
lnexpert workers often think they can make the tool life longer by making more, shallower passes instead of fewer, deeper passes.

“With titanium, it is true.... the opposite.”

Because of work hardening and heat conductivity, the most common cause of excessive tool wear is working with chips that are too small and thin.
Shallow cuts cause the tool to slide along the surface, with high pressure on cutting and heat.This fact must be noted for the last pass, which must not be too thin, because, in this case, the material would tend to refuse the tool and make the operation impossible.
On the other hand, titanium accepts deep cuts with a thick and well defined chip. Limits may be posed by high torque rates and consequent high power input requirements.lt is therefore useful to break chip into smaller pieces, especially during roughing passes.ln such cases, the chip-breaker is necessary as it considerably reduces the pressure on the cutting edge.

Turning

The tool should protrude as little as possible in order to avoid deflection to stop as far as possible titanium from scraping against the side of the tool.
Use tips with big radius (1.2) for the first cuts.
To obtain a good surface finishing, use tools with tips with a wide radius, but remember that such tools tend to increase work piece deflection. We recommend tips, Sandvik H13A or similar.
The tool should be kept constantly supplied with a strong flow of cutting fluid, directed towards the contact zone between the work piece and the tool.
A water solution containing 5% sodium nitrate, or a 5% oil emulsion in water is used. For turning, live centres should be used because the dead centres cause the tool to seize up.

Front milling

The working life of tools used for front milling can be prolonged by always using a device for compensating play on the feed screw.
The titanium chips tend to weld to the cutting edge of the milling tool and when the cutting edge enters the metal, chips are dislodged and take with them part of the cutting edge. This is especially pronounced with carbide tools.
As a result, the increased cutting speed that can be obtained with carbide tools compared with high-speed steel tools does not always make up for the additional costs of wear; it is therefore advisable to try both types of tools to find out which is more suitable for the different cases. We recommend the same tips as used for turning. Sandvik H13A or similar.
Milling with feed screw play compensation produces a fine chip when the teeth of the cutting tool leave the work piece, thus reducing the tendency of the chip to weld to the cutting edge.
As in all titanium machining operations, sharp tools must be used in order to reduce rubbing and welding. The bottom rake angle or front milling clearance angles must be greater than those used for steel. Use a water-based refrigerant.

Front milling

				HIGH-SPEED TOOLS			CARBIDE TOOLS
							Uncoated
							Speed
Material	Hardness	Condition	Cutting	Speed	Forward	Tool material	Brazed	Bit	Forward	Grade om
			depth		travel		insert	insert	travel	Tool material
Ti	HB		mm	m/min	mm per tooth	ISO	m/min	m/min	mm per tooth	ISO
Grade 1	110-170	Annealed
Grade 11
			1	53	.15	S9 S11	160	180	.13	K10 M20
			4	41	.23	S9 S11	120	135	.25	K20 M30
			8	32	.30	S9 S11	85	105	.40	K30 M40
Grade 2	140-200	Annealed
Grade 3
Grade 7			1	44	.102	S4 S2	120	135	.102	K10 M20
			4	34	.15	S4 S2	90	100	.15	K10 M30
			8	26	.20	S4 S2	60	76	.20	K20 M30
Grade 4	200-275	Annealed
Grade 12
			1	32	.102	S4 S2	100	105	.102	K10 M20
			4	24	.15	S4 S2	84	90	.15	K20 M30
			8	18	.20	S4 S2	58	72	.20	K20 M30
a alloys and	300-340	Annealed	1	21	.102	S9 S11	79	88	.102	K10 M20
a - b alloys			4	17	.15	S9 S11	69	73	.15	K20 M30
(e.g. gr5, 23)			8	12	.20	S9 S11	46	56	.20	K20 M20
a alloys and	310-350	Annealed
a - b alloys
(e.g. gr5, 23)			1	17	.102	S9 S11	52	56	.102	K10 M20
			4	14	.15	S9 S11	40	44	.15	K20 M30
			8	11	.20	S9 S11	29	35	.20	K20 M30

*) Cutting depths are measured parallel to the cutting axis.
Global Metal Trading Norway AS is not responsible for the correctness and accuracy of this information. The tables are guidance only. All numbers are approximate figures.

Front milling

HIGH-SPEED TOOLS			CARBIDE TOOLS
			Uncoated
			Speed
Material	Hardness	Condition	Cutting	Speed	Forward	Tool material	Brazed	Bit	Forward	Grade om
			depth		travel		insert	insert	travel	Tool material
Ti	HB		mm	m/min	mm per tooth	ISO	m/min	m/min	mm per tooth	ISO
a alloys and	320-370	Annealed
a - b alloys			1	14	.075	S9 S11	44	49	.102	K10 M20
(e.g. gr5, 23)			4	11	.13	S9 S11	34	37	.15	K20 M30
			8	8	.18	S9 S11	24	29	.20	K30 M30
a alloys and	320-380	Annealed
a - b alloys			1	11	.075	S9 S11	37	40	.102	K10 M20
(e.g. gr5, 23)			4	8	.13	S9 S11	27	30	.15	K20 M30
			8	6	.18	S9 S11	20	24	.20	K20 M30
a alloys and	320-380	Quenched
a - b alloys		and aged	1	17	.075	S9 S11	44	49	.102	K10 M20
(e.g. gr5, 23)			4	15	.13	S9 S11	34	37	.15	K20 M30
			8	12	.18	S9 S11	24	28	.20	K20 M30
a alloys and	375-440	Quenched
a - b alloys		and aged	1	9	.050	S9 S11	30	32	.102	K10 M20
(e.g. gr5, 23)			4	8	.102	S9 S11	23	24	.15	K10 M20
			8	6	.15	S9 S11	15	18	.20	K20 M30
b alloys	275-350	Annealed	1	12	.075	S9 S11	40	44	.102	K10 M20
( Ti beta – C)		or quenched	4	9	.13	S9 S11	30	34	.15	K10 M20
			8	6	.18	S9 S11	21	26	.20	K20 M30
b alloys	350-440	Quenched	1	9	.050		24	27	.102	K10 M20
( Ti beta – C)		and aged	4	8	.102		18	20	.15	K10 M20
			8	6	.15		12	15	.20	K20 M30

(*) Cutting depths are measured parallel to the cutting axis.
Global Metal Trading Norway AS is not responsible for the correctness and accuracy of this information. The tables are guidance only. All numbers are approximate figures.

Slot milling

For titanium slot milling, high-speed steel cutting tools are normally used, as short as possible.
As in this type of machining ratio between length of the cutting edge and the diameter is very high, there is a great deflection of the tool.
This condition is extremely critic when carbide tools are used.
The cutting tools should have slots sufficient to prevent the tools being clogged up with chips and therefore malfunction of tool. The cutting tools that are up to 25 mm in diameter should have three or four slots.

Drilling

lt is very important that the tips should be kept sharp and clean, because drilling of titanium alloys could be difficult unless the necessary preparations are made.
A blunt or not very sharp tip or with dirty sides stops the flow of chips along the slots.
Granular or opaque chips show that tip is blunt.
The length of the tip should be just long enough for the hole to be drilled, and should allow the chips to flow freely.

During drilling, the following precautions should be taken:
1. When drilling deep holes, choose points with internal channels that enable a supply of lubricant to be delivered.
2. Do not run the tool in the hole, unless cutting operations are being carried out.
3. Drill at low speeds.
4. If the lubrication is insufficient, remove the chips at regular intervals.
5. When drilling through holes, remove the tip before breaking the final section in order to lubricate the hole and     remove the chips; complete the drilling task at a low speed.

Drilling

Material	Hardness	Condition	Speed	Forward travel							Tool	Tool
				mm per revolution							material	geometry
				Nominal diameter om holes
Ti	HB		m/min	3+5	6+11	12+18	19+24	25,4+36	37+50	51,75	ISO
				mm	mm	mm	mm	mm	mm	mm
Grade 1
Grade 11	110-170	Annealed	30	0,01	0,05	0,13	0,17	0,20	0,25	0,33	S2, S3	AT* 180°
												AS 7°
Grade 2	140-200	Annealed	24	0,20	0,07	0,15	0,17	0,20	0,25	0,33	S2, S3	AT* 180°
Grade 3												AS 7°
Grade 7
Grade 4	200-275	Annealed	15	0,05	0,12	0,15	0,17	0,20	0,25	0,33	S2, S3	AT* 180°
Grade 12												AS 7°
3Al-2,5V	200-260	Annealed	15	0,05	0,12	0,15	0,20	0,22	0,25	0,30	S2, S3	AT* 180°
												AS 7°
5Al-2,5Sn	300-340	Annealed	12	0,05	0,12	0,15	0,17	0,20	0,25	0,27	S2, S3	AT* 180°
5Al-2,5Sn ELI												AS 7°
6Al-2Cb-1Ta-1Mo
4A1-3Mo-1V
6Al-4V	310-350	Annealed	9	0,05	0,12	0,15	0,17	0,20	0,22	0,25	S2, S3	AT* 180°
8Mn												AS 7°
7Al-4Mo	320-370	Annealed	6	0,05	0,12	0,15	0,17	0,20	0,22	0,25	S2, S3	AT* 180°
8Al-1Mo-lV												AS 7°
6Al-6V-2Sn
lAl-8V-5Fe	320-380	Annealed	4	0,05	0,10	0,12	0,15	0,17	0,20	0,22	S9, S11	AT* 180°
												AS 7°
6Al-4V	350-400	Quenched	8	0,02	0,05	0,10	0,12	0,15	0,17	0,20	S9, S11	AT* 180°
		and aged										AS 7°
6Al-6V-2Sn	375-420	Quenched	6	0,02	0,05	0,07	0,10	0,10	0,12	0,12	S9, S11	AT* 180°
7Al-4Mo		and aged										AS 7°
4Al-3Mo-1V
lAl-8V-5Fe	375-440	Quenched	4	0,01	0,02	0,03	0,03	0,12	0,12	0,07	S9, S11	AT* 180°
		and aged										AS 7°
l3V-11Cr-3Al	310-350	Annealed	6,00	0,02	0,07	0,10	0,12	0,15	0,17	0,20	S2, S3	AT* 180°
												AS 7°
lo3V-11Cr-3Al	375-440	Quenched	4	0,01	0,02	0,03	0,03	0,12	0,12	0,07	S2, S3	AT* 180°
		and aged										AS 7°

* AT = Angle between cutting surfaces
Global Metal Trading Norway AS is not responsible for the correctness and accuracy of this information. The tables are guidance only. All numbers are approximate figures.

Tapping

To obtain good tapping results, the holes must be straight and clean because variations in diameter and conical holes are harmful for this operation.
Good threads can be obtained by counteracting the tendency of titanium to scrape along the back of the male part and by creating the conditions for a free flow of chips along the slot. Otherwise, the threads will be long and weak, the holes will be undersized and the tool will seize up, so that the male parts break.
The use of nitrided males reduces the sticking to the back of male parts. Using a male part with interrupted threads also helps to minimize the rubbing tendency.
Seizing up can be reduced if using male parts with a spiral thread. Much material can be removed if the outfeed sides of the slots are well sharpened. To obtain adequate removal, use male parts with a two slot-spiral thread with diameters of up to 20 mm. For greater dimensions, use male parts with three slots.
For cutting fluid, use sulphurized or chlorinated mineral oil and remove the lubricating oil with a degreasing agent, such as acetone, before heat treatment.

Boring

The holes that have been pre-drilled or milled to be bored must be downsized by between 0.25 to 0.5 mm. Standard high-speed steel reamers and carbide reamers have a good performance, except when the groove angle must be 10°. To achieve the greatest space between teeth in order to eliminate chips, choose reamers with the minimum number of slots for a given dimension.

Broaching

Just as for the other titanium machining tasks, the machine tool and the titanium component must be stiff in order to ensure a high standard of broaching.
The broaches must also be wet sharped, to improve the standard of finishing work and performance.
During broaching, a strong flow of refrigerant prolongs the life of the broach and reduces its tendency to scrape.
For a non-continuous cutting like broaching, titanium chips tend to stick to the tool. This increases wear to the back.
Both the broaches and the broach slits must be checked regularly for sígns of scratching; scratches and sticking chips are signs of wear. Consequently, regular checks will prevent poor quality finishing work, rapid tool wear and loss of tolerances.

Grinding

The main rules for grinding are:
1. Use wheels with very sharp cutting edges
2. Use wheels with the greatest possible diameter and thickness
3. Use wheels as hard as possible
4. Use high-powered grinding shafts
    Lower grinding speeds than those used for steel will help to improve grinding performance.

The main reasons for using lower grinding speeds with titanium are:
1. high temperatures that develop in the interface between the chip and the abrasive
2. abrasive nature of titanium
3. wheel gumming

Nitrite-amine based cutting fluids have been found to be effective for many machining tasks.
Owing to fire hazards, if grinding oil is used during titanium grinding, especially at high speeds, the following precautions must be taken:
1. Fit extra cutting fluid conduits in order to extinguish the greater number of sparks;
2. If possible, install filters in order to eliminate fine titanium particles from the cutting fluids;
3. Clean frequently titanium powder off the external surfaces of the machines and change the oil more frequently than     for steels
4. Keep sand near machine, in order to put out any fires.

When grinding titanium, even if an excelient surface finishing is obtained, there is always the risk of obtaining poor resistance to metal fatigue; this is mainly due to the residual stress on ground surfaces.
ln order to reduce residual stress on ground titanium surfaces, use carburundum wheels, wheel edge speeds between 10 and 20 m/s and shallow passes; good results are obtained by using the following values: start with a 0.025 mm to 0.05 mm passes, followed by 0.013 mm, 0.01 mm, 0.0075 mm, 0.005 mm, and 0.0025 passes. The last pass must produce no sparks.
After grinding, it is preferable to pickle with 2% HF and 10% HNO3 water solution.

Cylindrical grinding

Material	Hardness	Condition	Grinding	Piece	Pass	Transversal	Grinding
			Wheel	rotation	depth	movement	wheel
			speed				identification
						Width om the	symbol
						wheel per	(*)
						workpiece
Ti	HB		m/sec	m/min	mm	revolution	ISO
Grad   1					Roughing
2					.025	1/5
3	110-275	Annealed	15-20	15-30			C60JV
4
7-11					Finishing	1/10
12					.013 max
					Roughing
	300-400	Annealed	15-20	15-30	.025	1/5
		or quenched					C60JV
		and aged			Finishing
					.013 max	1/10
					Roughing
	275-400	Annealed	15-20	15-30	.025	1/5
		or quenched					C60JV
		and aged			Finishing
					.013 max	1/10

Global Metal Trading Norway AS is not responsible for the correctness and accuracy of this information. The tables are guidance only. All numbers are approximate figures.
WARNING: if titanium fragments are exposed to flames they can catch fire; do not use water or liquid extinguishers to put out the  flames.
(*)  The wheels are recommended for lubricated grinding of work pieces between 50 and 100 mm in diameter.
For dry grinding use a softer grade.
For work pieces with larger diameters use softer grades and/or coarser grains.
For work pieces with smaller diameters use harder grades.
The recommended grinding wheels can also be used for plunge grinding.

Flat grinding
Grinding wheels axis: Vertical
Work piece table: Rotating

Material	Hardness	Condition	Grinding	Workpiece	Depth	Operation	Wheel identification
			Wheel	rotation	om pass		symbol
			speed	speed	for each
					table		Small	Wide
					rotation		working area	working area
Ti	HB		m/sec	m/min	mm		ISO	ISO
Grade: 1,2,3,4						Roughing	C36HV	C36GV
7,11,12	110-275	Annealed	18-30	15-30	.013-.025
						Finishing	C60IV	C60HV
		Annealed				Roughing	C36HV	C36GV
	300-440	or quenched	18-30	15-30	.013-.025
		and aged
						Finishing	C60IV	C60HV
		Annealed				Roughing	C36HV	C36GV
	275-440	or quenched	18-30	15-30	.013-.025
		and aged
						Finishing	C60IV	C60HV
Mouldings
		As cast				Roughing	C36HV	C36GV
grade 3	150-250	or melted	18-30	15-30	.013-.025
		and annealed
grade 7-11						Finishing	C60IV	C60HV

Global Metal Trading Norway AS is not responsible for the correctness and accuracy of this information. The tables are guidance only. All numbers are approximate figures.

Standard classification system

Grinding wheels

51

A

36

L

5

V

23

INITIAL CODE

TYPE OF

GRAIN SIZE

HARDNESS

STRUCTURE

BONDING

SYMBOL OM

NUMBER

ABRASIVE

Coarse

Medium

Fine

Extra

Soft

Medium

Hard

Dense

Wide

AGENT

MANUFACTURER

Number

A

10

36

70

220

A

I

Q

1

9

V: vitrified

used by the

Aliminium

12

46

80

240

B

J

R

2

10

Manufacture

oxide

14

54

90

280

C

H

S

3

11

to

D

L

T

4

12

Distinguish

E

Medium

U

5

13

the type

F

N

V

6

14

of abrasive

G

O

W

7

15

(optional)

HARDNESS

P

X

8

etc.

Y

Z

Global Metal Trading Norway AS is not responsible for the correctness and accuracy of this information. The tables are guidance only. All numbers are approximate figures.