Grinding and Drilling Machines

General Engineering (Manufacturing)

Grinding machines are material removal tool used for surficial removal in low rate. They uses abrasives as primary material to remove material. Grinding Machines are extremely useful for matching dimensional tolerance, fitting, surface finish and tool sharpening. Grinding is a finishing operation which utilizes a multi-points randomly oriented abrasives in a form of grinding wheel to remove materials for performing finishing operation.

Manual Grinder are used to grind general tools and materials which does not require much dimensional accuracy. Material is held by a hand or fixture and fed in cylindrical of flat face of the grinding wheel.

A manual grinder

Technical specifications:

Configurations of a manual grinder

Surface grinding machine is used to finish relatively larger flat surfaces mounted over an x-y-table. The grinding wheel mounted on the horizontal shaft is feed towards the workpiece to perform finishing operation. The grinding wheel is characterized by the material, grit size, and type of bond, spacing between the abrasives and bonding material. Grinding operation consumes highest specific power among the commonly used conventional machining operations.

A surface grinding machine

Technical specifications:

Configurations of a surface grinder

Grinding Capacity : L ×W× H (mm × mm× mm)

500×250×330

Longitudinal table travel (mm)

520

Cross table travel (mm)

275 

Max. distance from the spindle center to the worktable surface (mm)

410

Safety load to bench (in Kg) 

100 

Table size (mm × mm)

500 × 250 

T- slot

12 ×1 mm × no.

Bench speed (m/min)

3-23 

Cross auto feed (mm/div.)

0.02

Grinding wheel size (D × W× d)  (mm × mm× mm)

200×16×32 

Spindle speed (RPM)

2850

Max. movement of vertical mechanism (mm)

410

Vertical fine adjustment revolution (mm)

0.15 

Vertical per fine adjustment graduation (mm)

0.002 

Spindle motor power (Kw)

1.1 kw

Overall dimensions (mm × mm× mm)

1550 × 1180 × 1840 

Unlike a magnetic fixture or any other fixture in a surface grinder, in centerless grinder there is no such fixture for holding the workpiece. The workpiece, which can be a delicate part not suitable to hold in a fixture or an irregular shape, is hole between the grinding wheel (cutting wheel) and a regulating wheel. Axis of the wheels are not exactly parallel rather there is an angle between two wheels, which provides automatic feed during the cutting operation. Figure below shows a centerless grinding machine.

A centerless grinding machine

Technical specifications:

Configuration of a typical centerless grinding machine

Sample Specification

Grinding capacity 

Diameter: 2 mm (min.)

100 mm (max.)

Grinding wheel diameter (mm)

Width (mm)

Bore (mm)

350

100

127

Regulating wheel diameter (mm)

Width (mm)

Bore (mm)

230 

100 

76.2 

Speed (RPM)

20-220 (Step less Variable)

Swivel Angle

Swivel of grinding dresser – +/- 5°

Swivel of regulating dresser – +/- 5°

Regulating swivel angle

+/- 5° Vertical

Regulating swivel angle

+/- 5° Horizontal

Dresser operation

Grinding & Regulating Wheel – Hydraulics

Power requirement (KW)

Grinding Wheel Motor – 5.5 

Regulating wheel motor (KW)

0.75 DC

Coolant pump motor (KW)

0.12 

Power pack pump (KW)

Dimensions 

Width (mm)

Height (mm)

Net weight (Kg)

0.18 

Length (mm):1900 

1500 

2000 

2200 (Approx.)

As name suggests these kind of grinders are specifically designed to finish the internal surfaces such as internal holes and bores. The inner surfaces are finished by passing the grinding tool in the rotating workpiece and material removal occurs similar to any grinding operation. Sometime it is possible to use multiple wheels for specific applications. The typical applications of internal grinding include precise finishing of pipes, tubes, bearing races, bushings, etc.

An internal grinding machine

Technical specifications:

Configuration of a typical internal grinding machine

General

Max job length (mm)

50

Max grinding length (mm)

50 

Height of centre (mm)

150

Internal grinding Spindle

Spindle diameter 

60/80

RPM if ID spindle

12500/18000/28000

HP of wheel

2 HP

Work head

Swivel range

45O 

Spindle morse taper

MT 3

No. of speed

3/ Variable

HP of motor

0.5/ 1 HP

Total weight (Kg)

1000

Table speed

Hydraulic infinitive variable speed

Optional 

Shoe magnetic centre less chucking system/ Diaphragm chucking system/ Three Jaw chuck/ four jaw chuck /Hydraulic collets/ manual collets /hydraulic chuck

Slide ways coated with ‘TURCITE’

Variable speed control AC drive in work head with digital read out

Automatic grinding cycle

Hydraulic size unit in cross slide, spark out, fast retract / CNC, HMI & PLC operated cross slide

Rapid     unit

DRO in cross slide

Micro feeding attachment

Magnetic separate / paper band filter/ magnetic Separate with paper band filter

These are special purpose grinder machine designed to grind highly eccentric profiles accurately, there design is almost similar to big lathe having grinder wheel & motor arrangement in tool post. It has arrangement of a grinding wheel and tool which have radial and transverse movement to grind and finish complex surface like crank shaft of engine.

A crankshaft grinding machine

Technical specifications:

Configurations of a typical crankshaft grinding machine

Height of centre from the table (mm)

180 

Maximum head offset (mm)

70 

Maximum distance between chuck (mm)

780 

Maximum distance between centers (mm)

850 

Diameter of self-centering chucks (mm)

160 

Diameter of grinding wheel (mm)

600 

Grinding head traverse with hydraulic (mm)

80 

Work head spindle rotation speed (variable) (RPM)

20 – 110 

Automatic table movement

—-

Grinding wheel spindle rotation (RPM)

1050 

Grinding wheel motor (RPM)

2 HP / 1440 

Work head motor (RPM)

0.25 HP 1440 

Coolant pump motor (RPM)

0.13 HP / 2800 

Hyd. power motor (grinding wheel slide) (RPM)

0.5HP/ 1440 

Length of the machine     (mm)

1850 

Width of the machine (mm)

1100 

Height of the machine (mm)

1500 

Net weight (Ton)

1.5

Gross weight (Ton)

CNC Grinder again digital upgrade of Manual grinders where, job handling, grinder wheel/tools engaging etc. all operation are controlled electrically by a computer onboard. These are advantageous for precision grinding and in complex profiles. Grinding position and material removal are al indicated using computer aided design and data is fed to the CNC Grinder to get the job done automatically.

A CNC grinder machine

 Technical specifications:

Configuration of a CNC grinding machine

Sample Specifications

Centre height (mm)

175 

Admit between centre (mm)

400 

Swiveling range (degrees)

-15 to +225 

B- axis resolution (degrees)

0.0001 

Grinding wheel size (OD × thick × bore) left side (mm)

500 × 40 (50 ROS) × 203.2 

Grinding wheel size (OD × thick× bore) right side (mm)

500 ×40 (50 ROS) × 203.2

Spindle motor power (built in type) (Kw)

7.5 

Peripheral (surface) speed (m/sec)

60 

Floor space front × depth (basic machine) (mm)

3100 × 2800 

Machine weight (approximate) (kg)

4500 

Drilling Machines are used to drill precise holes in a workpiece. Prior to drilling, the work is centre punched for indent marking. A drill bit with the requisite diameter is mounted in a check and rotated with an electric motor set to the required speed. To cut a hole in the work piece, the revolving drill bit is lowered using a rack and pinion system. It also has a depth limiter.

A hole drilling machine

(Image source: https://ravimachines.com/product/pillar-drill-machine-16-mm/)

 

Technical specifications:

Configuration of a hole drilling machine (Source: https://ravimachines.com/product/pillar-drill-machine-16-mm/)

Drilling capacity (mm)

16

Column diameter (mm)

58

Spindle nos. to table dist. (mm)

450

Spindle nose to best dist. (mm)

670

Spindle center to pillar face dist. (mm)

160

Table travel (mm)

450

Spindle hole taper

MT-2

Spindle speeds (RPM ×steps)

135-2475×6

Table size (mm)

230 

Base size machine area (mm× mm)

190 ×220

Overall base size (mm× mm)

230 ×370

Spindle travel (mm)

100

Column length (mm)

920

Overall height with fully

1100

V-belt section (size)

A-37

Weight (approx.) (Kg)

60 

Motor (HP)

0.75 

Spindle dia. (mm)

54 

Drilling and thread-making machines are specialized machines. Taps are used as a cutting tool and are installed on a chuck with a motor. They can also move in translation. The work piece is drilled for a standard hole in a separate drilling machine, and the threading is completed on this machine or with a combination drill tap tool. When tapping and drilling, it’s crucial to utilize lubrication.

A drill tap machining center

Technical specifications:

Configuration of a drill tap machining center

Maximum tapping diameter (mm)

M14mm

Morse short taper of spindle

B16

Max. distance between spindle and column (mm)

13

Spindle travel (mm)

38

Column diameter (mm)

50

Size of worktable (mm × mm)

240×240

Max. distance spindle to table (mm)

220

Max. distance spindle to base (mm)

320

Size of worktable base (mm)

180×200

Spindle speed (RPM)

260, 440, 750

Motor (HP)

0.5

Overall size (mm× mm× mm)

495 ×250 ×825

Weight (Kg)

48