FAQ

Centreless grinding is a precision machining process that removes material from the outer diameter of cylindrical workpieces without using centres or fixtures to hold the part in place. Unlike conventional cylindrical grinding, where the workpiece is secured between centres or in a chuck, in centreless grinding, the workpiece rests on a work blade. Two wheels guide it: a grinding wheel and a regulating wheel, also often referred to as a control wheel.

The grinding wheel rotates at high speed to remove material, while the regulating wheel rotates at a much slower speed to control the workpiece’s rotation and feed rate. Often, the regulating wheel is inclined to adjust the material feed rate.

The work blade provides support at the correct angle, creating a stable “grinding zone” for precision machining.

Visit the Centreless ( or Centerless) Grinding Machine Section : https://www.rk-int.com/product-category/grinding/centreless/

There are many different options for bandsaws, depending on materials and sizes being cut.

• Vertical Bandsaws - These range from benchtop machines for the hobbyist (generally cutting wood or plastics) right up to huge machines to cut metals ( ferrous and non ferrous). The basic design is the same where a single vertical bandsaw blade is tensioned across 2, 3 or 4 band wheels giving a maximum height under the guides, and a maximum depth from the frame to the blade ( throat). Please see example machines here: vertical-bandsaws
• Horizontal Bandsaws - again these come in a small portable format for site work, right through to machine you can park a car under and saw it in half! The process is the same with machine operation coming in a manual (pull down saw), Gravity feed (saw frame descends by itself and the rate is controlled via a valve on the hydraulic circuit), semi automatic (hydraulic down feed of the saw frame and hydraulic operated vice) and fully automatic (same as the semi automatic machines but with the addition of bar feeding to allow batch cutting operations. These can also be full enclosed CNC controlled bandsaws. Horizontal bandsaws can also do mitre cuts to allow for cutting angles on sections or beams. Please see example machines here: Horizontal Bandsaws

NO. Many factors come into play such as structure, blade size, blade speeds and coolants.

• Structure - Lighter duty machines running hi speed bandsaw blades will be ideal for woods, plastics and some non-ferrous metals
• Blade size - Trying to cut a heavy piece of material with a 13mm wide blade just doesn't work. The wider the blade the stronger it is (beam strength).
• Blade Speeds - Hi speed machines cut soft materials but when you start cutting mild steel, stainless steels or other exotic metals, then the blade speed has to be slow ( say 15 -70 m/min). These machine also need torque ( power) to drive the blade through the material.
• Coolants - a vital item needed to cut anything that generates heat or is abrasive.  Anything metal will need flood coolant or a mist lubrication system.

Some examples here: Wood Bandsaws   Metal Bandsaw     Aluminium Bandsaws -Vertical

Depends on the daily work really. If you do lots of one offs, and quick cutting jobs ( like box sections or tube), then its quick and easy to use a pull down saw. If your cut time is longer, like heavy wall sections or solids, then let the bandsaw do the sawing whilst you go do something else!

Some bandsaws have both options fitted ( such as the Macc CSO range) The Macc 280CSO is a popular one. Macc 280CSO

Gravity feed machines are straight cutting or mitre capability ( swivel head), as are semi automatic bandsaws. So the fundamental design is all the same. However the key difference on a semi automatic bandsaw is the hydraulic operation of the vice and the saw frame.

Operation:

Gravity feed bandsaw - you lift the saw frame up to clear the work area, then place your work in the saw and manually clamp the vice. Press the start button to run the blade and coolant, then open the needle valve to gently descend through the job stopping the blade and coolant automatically once its hit the bottom.

Semi-automatic bandsaw - the saw frame is powered to the raised position ready for the work piece to be loaded. Once ready, you press the start button and the blade starts, vices will clamp (hydraulically) and the saw frame will descend through the workpiece. Once the cut is complete. the saw frame will raise back up to a pre-set position ready to start another cut, and the vice will unclamp. These controls can be changed to suit different jobs.

Another thing to consider is the size of saw needed. If your cutting larger products then the actual saw frame will be much bigger and difficult to handle. So the need for hydraulic lifting becomes vital.

Some examples can be found here: Horizontal Bandsaws UK

Horizontal machines can still be made with a 2 speed motor giving simple operation if you were doing say mild steel and stainless steels. They are typically somewhere around 40 and 80 M/min.

Better speed options give better results and longer blade life on more varied materials. A typical speed option in the modern day is to use a frequency inverter to control motor speed. This might allow speeds from 15 -90 M/min giving great results on the harder metals.

Vertical bandsaws can have invertors or mechanical variators and even gearboxes to allow for high and low ranges. Again, speeds are crucial to the material your cutting. If only ferrous metals, then slower speed ranges will be needed. If your cutting woods, metals and plastics you'll need a full speed range from 20 - 1200 m/min. These are available and would have invertors and gearboxes to give speed and torque control.

Industrial circular saws come in 2 main types. Ferrous and non-ferrous. Each range then has the option of manual, semi automatic or fully automatic.

Metal saws for steels - These are generally available with a blade range of 250 -350mm diameter and run slower speeds for mild or stainless steels. Typical 2 speed machines run a 20 / 40 rpm and would have a flood coolant system. Commonly known as chop saws, these use solid SHSS circular blades and have the tooth pitch cut into them. The blades can be supplied with many different coatings depending on the materials they need to cut.

Circular saws for non-ferrous / plastics - These machine are normally single speed and run at a much higher speed. Normally @ 3000 rpm depending on blade diameter. The suitable blades for this type of machine would be TCT (Tungsten Carbide Tipped) and would be quite course in pitch. TCT blades are used for wood, aluminium and plastics with the tooth form on the blade being different for each application. TCT blade can cut dry or a simple venturi mist spray can be used to assist with lubrication.

Both types of circular saw blade can be sharpened, with the HSS slow speed blades being able to be re-cut if damaged or severely worn.

A couple of reasons really, the main being they are quick and can potentially give a better finish.

• Non ferrous circular saws are much quicker than a bandsaw and give a better cut, but they are limited to capacity. If you have a large section to cut the bandsaw might be needed.
• High end circular saws can be expensive to purchase, so make sure you can justify the limited capacity.
• Smaller chop saws for steel are just a common way to saw smaller box section, angle and tube and take up less floor space than a bigger bandsaw.

SHSS blades ( the most common type of chop saw blade) normally used for cutting mild steel or stainless steels would tend to run between 20-80 rpm. Simple machine like a Macc 300E could have a 2 speed motor with a standard setting of 40 & 80 rpm. If you cut a fair bit of stainless steel, then a slower speed motor should be chosen. Macc offer the option of 20 & 40 rpm on some models.

SHSS blades (super high speed steel) can be provided with many different coatings to increase hardness, reduce friction and heat build up. Examples of these would be TiN (Titanium Nitride) or TiCN (Titanium Carbonitride). Whilst there are plenty of options, the gold coloured TiN coating is certainly a popular one.

TCT blades (Tungsten Carbide Tipped) can be used on high speed machines with a typical blade speed of 1,500 -3000 rpm. TCT blades can also be supplied with specialist coatings.