Technical Specifications

Reamers

TECHNICAL SUPPLY CONDITIONS OF "DAGGER REAMERS"
1. Reamers are normally supplied with straight flutes or helical flutes for RH cutting.
2. Intermediate diameters,if ordered,shall be supplied with the same dimensions as the next larger standard size.
3. Non standard or special reamers are manufactured against specific orders.
4. Morse taper Shank dimensions are according to IS: 1715 - Dimensions for self-holding tapers.
4.1 Driving square according to IS: 1850 - Dimensions for Shank diameters and driving squares for rotating tools.

5. Other general requirements are maintained according to IS: 5443 - Technical supply conditions for high speed steel reamers.
5.1 Hardness :
Cutting Portion: 760 Hv to 900 Hv.
Shank portion : 240Hv to Maximum hardness equal to cutting portion (in case of one piece construction)
Tang of Morse Taper: Sizes below 10mm 185 Hv minimum and for sizes 10mm and above 300HV to 450 HV
Driving tenon: 240Hv to maximum hardness equal to cutting portion.

5.2 Reamers are normally supplied with m6 tolerance on cutting portion and are expected to produce H8 holes; by selection will also be suitable for H7 holes.
5.3 Run Out Tolerance:
5.4 Reamers shall have a black taper at the rate of 0.010 to 0.020 per 100 mm cutting edge length up to 30 mm diameter and 0.20 to 0.030 per 100 mm for sizes above 30 mm diameter.

6. Reamers according to DIN, BS and ANS are also manufactured against specific orders.

Run Out Tolerance

Reamer Diameter Shell reamers and Machine Reamers with parallel Shank/ taper Shank Hand Reamer
Over up to & Including On Bevel Edge On Diameter On Shank Diameter On Taper lead
1 3 0.020 0.005 0.010 0.030
3 6 0.020 0.006 0.012 0.030
6 10 0.025 0.008 0.015 0.030
10 18 0.025 0.008 0.018 0.036
18 30 0.030 0.009 0.021 0.042
30 50 0.030 0.011 0.025 0.050
50 80 0.040 0.013 0.025 0.050
80 120 0.040 0.015    

TOLERANCE FOR SPECIAL REAMERS

Ref : IS 5443 - 1994

General :-
Unless otherwise specified, the diameter of the cutting portion of the reamer shall have a tolerance of m6. For determining the tolerance for the diameter of the cutting portion of the reamers where of the cuttiing portion of the reamers where a grade of accuracy other than m6 is required. It is impossible to infer in advance the tolerance of a hole produced by a particular reamer because the actual diameter produced by the reamer depends upon a number of factors.

Some of the factors which influence the accuracy og the hole diameter are as follows :-
(a) Type and amount of the material to be removed.
(b) Cutting edge design of the reamer.
(c) Method of mounting and operation.
(d) Condition of the reamer at the time of use, and
(e) Lubrication

these factors shall be taken into account while determining the special tolerance to be given on a reamer in order to get a hole of given tolerance.

METHOD OF DETERMINING THE SPECIAL TOLERANCE
The maximum limit for the reamer diameter = the maximum limit of the hole - 0.15 IT. The value of 0.15 IT is to be rounded to next higher value of 0.001mm.
The maximum limit for the reamer diameter = the maximum limit of the reamer- 0.35 IT. The value of 0.35 IT is to be rounded to next higher value of 0.001mm.

Example:-
For a 12H7 hole
IT=0.018 hole size Maximum limit = 12.018
Minimum limit = 12.000
Maximum limit of reamer diameter = maximum limit of the hole - 0.15 IT
= 12.018 - 0.15 * 0.018 = 12.018 - 0.0027
= 12.018 - 0.003 = 12.015
Minimum limit of reamer diameter = maximum limit of the reamer diameter - 0.35 IT
= 12.015 - 0.35 * 0.018 = 12.015 - 0.0063
= 12.015 - 0.007 = 12.008

RECOMMENDED UNDERSIZES FOR REAMING

Material Range of diameter of bore
From 3 Upto 5 Over 5 Upto 10 Over 10 Upto 20 Over 20 Upto 30 Over 30
Steel upto 70 kg /mm
Cast iron
Plastics-soft
0.1-0.2 0.2 0.2 0.3 0.4
Steel 70-100 Kg/ mm
Brass, Bronze
0.1-0.2 0.2 0.2 0.3 0.3
Copper, Light metals 0.1-0.2 0.3 0.3 0.4 0.5
Malleable cast iron 0.1-0.2 0.2 0.3 0.4 0.5
Palstic-hard 0.1-0.2 0.3 0.4 0.4 0.5
Steel Casting 0.1-0.2 0.2 0.2 0.2 0.3

Values shown are in mm.
To Obtain optimal surface quality when reaming hard material the above values for allowances to be halved and preferably performed in two operations pre-finishing and finishing. If pre- drill hole finish is obtained rough the above values may have to be increased slightly.

TYPICAL REAMER FAILURES:-

Observation Reason Remedy
Increased reamer wear, Variation of hole size such as Tapered oversize or bell-mounthed Check the reamer alignment Remove mis-alignment or use adjustable reamer holder.
Chatter mark. In the hole or poor quality of reamed hole Insucure holding of job of fixture. Excessive speed of reamer or Spindle Feed is too low. Improve all the reasons mentioned

REAMING FEEDS

Reaming feeds:- Feeds are usually much higher than those recommended for drilling the same material. i.e as much as 200 to 300% of drill feeds. Very low feed will result in more reamer wear. Very high feed may lower the finish and accuracy of hole. It is described to use high feed at the same time finish and accuracy should be achieved.

Diameter of reamer in mm Feed mm/ rev
Over Upto & loading Feed mm/ rev
- 4 0.06-0.2
4 6 0.10-0.3
6 10 0.12-0.4
10 16 0.16-0.6
16 20 0.20-0.8
20 25 0.24-1.0
25 40 0.30-1.2
40 63 0.40-1.2