A planer machine is another type of metalworking machine tool that uses linear relative motion (reciprocating) on a single-point cutting tool to the workpiece. Planer machines are very similar to shaper machines, which is why an article was published on their differences. Their major difference is that planer machines are larger and move the workpiece, while shaper machines rotate the cutting tool. This machine is also essential in machine shops, as many operations can be performed on it.
Well, in this reading, we’ll learn what a planer machine is, its applications, parts, diagrams, types, mechanisms, and how it works. We’ll also explore the advantages and disadvantages of planer machines.
Let’s begin!
What is a Planer Machine?
A planer machine is a heavy-duty, precision machine tool used to shape and level large, flat surfaces on metal or other workpieces. It works similarly to a shaper but is made specifically to handle heavier and larger workpieces. A planer’s main component is a cutting tool that is fixed on a table and mounted on a horizontal crossrail. The cutting tool removes material to produce a smooth and level surface by moving along the length of the workpiece in a linear, reciprocating motion.
It is a metalworking machine tool that uses linear relative motion between the workpiece and a single-point cutting tool to perform cutting operations on the workpiece. The invention of the planer is attributed to General Bentham, rendering it a crucial and essential machine tool in manufacturing.
Planers and shapers are comparable; however, planers are bigger and have a moving workpiece, whereas shapers have a moving cutting tool. It is possible to feed (move) the tool across the table in short, discrete, sideward movements at the end of each pass of the table because the tool-holding mechanism is mounted on a cross rail.
This allows the tool to be fed across the table. The cutting tool’s capability to be positioned at nearly any angle enables the creation of diverse grooves and surfaces. The duration and velocity of its table movement can also be adjusted. The planner machine falls under the category of heavy machinery designed to produce a flat surface on large and heavy work items.
Work items are set on the table, and the cutting tool is guided in the necessary directions: horizontal, vertical, and diagonal.
Planer Machine Applications
The planer machine can be used for any of the following applications:
- Working on massive components for the aerospace and shipbuilding industry.
- Producing precise, parallel surfaces on materials such as cast iron and steel.
- Machining heavy machinery parts, like guideways and machine beds.
- Manufacturing components for industrial equipment and machinery.
- High-precision machining in the heavy engineering industries.
- Fabricating parts for construction equipment and infrastructure.
- Large metal workpieces are smoothed and flattened on their surface.
- Restoring and repairing worn or damaged surfaces on large components.
Related: What is Shaping Machine? Its Diagram and How it Works
Components of Planer Machines
Below are the major parts of a planer machine:
Bed
The bed is like a box made of cast iron with cross ribs. The cast iron offers compressive strength to the part; it is very heavy in weight and very large. All other components of the machine are mounted like columns, and all moving parts are supported by the bed.
This bed is provided with accurate machine v-type or flat-type guideways for smooth sliding of the table. The bed houses the driving mechanism for the table; this bed is twice the length of the table, which makes the table slide on it.
Table
The table is a rectangular material made of cast iron with a machined top surface to locate the work accurately. A t-slot is also provided on the entire length of the table to properly hold the workpiece. Some holes are drilled on its surface at regular intervals to support the poppets and stop pins.
A hollowed space is provided to collect the chips and a groove is cut on its side for clamping planer reversing dogs at different positions. This is seen at each end of the table.
Planer tables are available in either single or two separate tables which are mounted on guideways and can reciprocate separately or together. The bed contains hydraulic bumpers at the end to stop the table from overrunning and give a cushioning effect.
Housing or Column
The housing is also like a box, vertically structured and fastened on each side of the bed. They are also known as uprights. This planer machine part is heavily ribbed to bear heavy load during the cutting operations. The front face of each housing is designed in precision ways to slide a cross rail up and down and also contains a two-side tool head to slide upon it. This column houses the cross-rail elevating screw, vertical, and cross-feed screws for tool heads. These screws are controlled by power or hand.
Cross Rail
A cross rail is a rigid cast iron that connects the two housings, which provides additional rigidity to the machine. It is designed to move up and down on the face of the housing using an elevating screw.
This planer machine part can be clamped at any position and it is parallel to the top surface of the table. The cross rail is provided with accurately machined guideways at its surface. It allows cross-feeding the tool head saddle using a screw.
Tool Head
This planer machine part is similar to that of the shaper machine in terms of construction and operation. This tool head is mounted on the cross rail by a saddle, which allows it to move crosswise to offer cross-feed. The swivel base is positioned on the saddles and it is graduated to 60 degrees on each side. Due to this, the swivel can be tilted at any desired angle for machining angular surfaces by rotating down the feed screw.
An apron is fixed on the face of the vertical slide, which may be swiveled up to 20 degrees on each side to give the tool clearance while working a vertical surface. The clapper block is hinged, which allows the clapper box to hold the tool post in which the cutting tool is held firmly.
Finally, a clipper block lifts the tool head upward during the return stroke to prevent the cutting edge of the tool from dragging on the work. The tool heads can move up and down by moving the cross rail up and down
Diagram of a Planer
Types of Planer Machines
The following are the common types of planer machines:
Double Housing Planer Machine
This is one of the most common types of planer machines used in most workshops. It comprises a long, heavy base having an accurately machined guideway that allows a table to reciprocate on it. The length is twice the length of the table. There are two vertical housings mounted close to the middle of the bed, one on each side, which are connected at the top by a cross member.
In the horizontal cross rail, two tool heads slide over the vertical faces of the housings. These tool heads can be operated with power or by hand in the crosswise or vertical direction to give a feed. Additionally, there are two other tool heads placed on the vertical face of the housing; they can move in a vertical and horizontal direction to offer the feed. Driving this planer table, a mechanical or hydraulic device may be used.
Open-side Planer Machine
These types of planer machines have only one housing on one side of the base. Unlike the double housing that enables two, three tool heads can be featured in this machine, and a single housing takes up the entire. However, it is rigid and robust enough to resist the forces.
The cross rail carries the toolhead, which can move vertically and horizontally and it can slide vertically along the guideways of the housing. Another tool head is fitted on the housing and it is also in the same direction as the other.
Pit Planer Machine
A pit type of planer machine has a massive construction in which the table is kept in a pit in a stationary position. The column that carries the cross rail reciprocates on a horizontal rail that is on both sides of the table.
The table of this machine is designed to feature very heavy work as it is made level with the floor. This helps heavy work to be easily loaded. The cross rail carries two tool heads and can be moved both vertically and horizontally to cut. A driving screw is used in this machine to drive the column using a motor.
Edge Planer Machine
An edge planer is known as a plate planer. It is used for squaring and beveling the edges of steel plates that are used in shipbuilding works and for different pressure vessels. The table that carries the workpiece remains stationary, and the work is clamped by air-operated clamps. The tool head that is mounted on the carriage moves towards two horizontal guideways on a base front. There is a space for the operator on the carriage to move along with it. The tool on the carriage reciprocates past the edge of the plate.
Divided Table Planer Machine
This machine consists of two tables on the bed that can reciprocate separately or together. This feature makes operation much faster, making it suitable for mass production work where identical work is to be performed. This is achieved by loading the work on one of the tables, and the other reciprocates past the cutting tool for the finishing work. The table stopped after the work was done and was removed by shifting the table to the end.
For heavy-duty and large jobs, the two tables will be clamped together and the reciprocating movement occurs under the tool for machining.
Planer Machine Mechanism
The following are the two major types of planer mechanisms:
- Table drive mechanism.
- Feeding mechanism.
The different table drive mechanisms include:
- Open and cross-belt drive.
- Reversible motor drive.
- Hydraulic drive.
Planer Machine Operations
The common operations performed on a planer machine include:
- Machining flat horizontal surfaces.
- Flat vertical surfaces.
- Angular surfaces and machining dovetails.
- Curved surface slots and grooves.
Planer Machine Specification:
The following, stated below, represent the specifications of planer machines:
- Distance between the two housings.
- The maximum length of the table travel.
- Height from the top of the table to the cross rail in its utmost position.
Related: What is Milling Machine? its Diagram & How it Works
Planer Machine Working Principle
Planer machines are known for their ability to handle large workpieces and produce accurate flat surfaces and slots. The workpiece is securely fixed to the machine table, and a single-point cutting tool is appropriately held in the tool post attached to the reciprocating ram.
The ram reciprocates, ensuring smooth back-and-forth movement. The ram’s quick return motion mechanism ensures smooth back-and-forth movement during the forward stroke, where the cutting tool engages with the material, removing the material to shape the workpiece.
During the return stroke, there is no cutting action, and this stroke is referred to as the idle stroke. This allows the cutting tool to reposition for the next pass without cutting into the material, preventing unnecessary wear and facilitating efficient machining.
How Does a Planer Machine Work?
The planer machine is a tool that operates on the principle of relative motion between the tool and the workpiece. It facilitates reciprocation, transverse feed movements, and gradual, sporadic transverse feed movements through rapid linear cutting motion. The machine consists of a stationary tool head, a moving worktable, a secure workpiece, and a single-point cutting tool.
When powered on, the worktable advances to facilitate the cutting stroke, while the return stroke is achieved by moving the worktable downward. The machine operates using two types of mechanisms: the table drive mechanism and the feeding mechanism.
The table mechanism can use an open belt drive, a reversible motor drive, or a hydraulic drive. The planer machine can perform operations on flat horizontal surfaces, flat vertical surfaces, angular surfaces and machining dovetails, curved surfaces, and slots and grooves.
Advantages
The following represent planer machines benefits:
- Good surface finish.
- Low maintenance requirement.
- Greater accuracy.
- More than one tool can be used on a workpiece.
Disadvantages
Despite the great advantages of planer machines, some limitations still occur. The following represent the disadvantages of planer machines
- Planer machines are expensive.
- It requires more power supply to work.
- A skilled worker is required.
- Only a single-point cutting tool can be used.
- Its operation is finite.