HOW TO SELECT A LATHE MACHINE
Some useful tips while choosing a Lathe Machine
- 1.It is important to identify which type of job & process are required by using lathe machine. i.e. type of material, Job dimensions, operations to be carried out on job, output required etc. basic analysis should be carried out.
- A lathe machine can do following processes on job: Turning, Facing, Taper Turning, Contour Turning, Form Turning, Chamfering, Cut Off, Threading like Inch, MM, DP & Module, Drilling, Knurling etc.
- 2. Spindle Bore:
- If your Job is to be passed through Spindle bore, spindle bore Inner Diameter should be compatible with job diameter. For example, if you are turning long metal rod, & if the rod has diameter of 50mm than spindle bore diameter should be 50mm & some more up to the rod could be passed from the spindle easily.
- The dimensions & weight of Job and Chuck are also important to consider the size of required spindle bore.
- 3. Center Height
- Center height is vertical space from center point of spindle bore to table of bed. Table of bed is where guide ways are located. Center height can be measured in mm or inch.
- Swing Over Bed: Center height is kind of radius whereas "swing over bed" is like diameter. Within this limits (swing over bed), a job can be turned / operated. In normal cases, it is preferable that "swing over bed" should be little more than "job diameter".
- If center height of lathe machine is to say, 250mm, than swing over bed is probably 250mm X 2 = 500mm. That concludes, a job with maximum of 500mm diameter can be turned, upon that machine. Although, "swing over cross slide" should be also taken into consideration in regards of job diameter & length.
- Swing Over Cross Slide: There will be Cross Slide & Saddle moving upon bed. Cross slide & Saddle "consumes" the space for the job on vertical dimension, So, Swing over cross slide = Swing over Bed - (less) vertical height of Cross Slide & Saddle. This is to keep in consideration when job has bigger length & width (dia.), for example shaft.
- Swing in Gap: There will be gap & also removable bridge in the bed, right below of the spindle nose at a machining side. So, Swing in Gap Bed = Space between Spindle bore Center point to bottom of gap bed (after removing bridge) (radius) x 2.
- 4. Admit Between Center (ABC) or Distance between Center (DBC)
- ABC is horizontal space between spindle dead center to tail stock dead center. This is the space where job will be turned or got operated.
- ABC is not bed length. ABC is working space of bed length. ABC is a part of total "bed length".
- While consider the ABC or DBC, there should also be consideration of chuck width. For Example if the job is 1000mm, width of chuck is 200mm, live center is 100mm, than ABC must be more than 1300mm according to requirement.
- 5. Bed
- There are many type of Beds are available. 2V & 2Flat type Bed is widely used. 2V & 2 Flat are guide ways of bed which is the most important part of bed. Saddle with Cross Slide & Compound slide, tail stock move upon guide ways.
- 6. Motor Power
- Motor Power is capacity of electric motor attached with the lathe. It can be either in HP (Horsepower) or kW (Kilo Watt). 1kW is equal to 1.34 HP approximately.
- Motor power has its final transmission of energy at spindle. Thus value of motor power has its effect on either "number of RPM of spindle" OR "torque of spindle".
- Certain higher number of RPM requires rigid & strong mechanism in lathe machine as well as higher motor power.
- Spindle Torque is required when the material of job is harder on scale or bigger on diameter or both.
- For some material like Aluminum, Brass or Copper, it is preferable in some cases to turn it with higher RPM. Electric motor is a main force behind no. of RPM along with mechanism of Lathe Machine.
- Where the job is heavier, for example, steel bar with (370mm dia. x 3500mm length) will weight approximately 2900 KGs, such heavier job needs higher motor power to turn heavy job whereas the RPM will be lower.