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MODULE-II
PLANNING ISSUES
•

Components of FMS
• Planning issues
• Computer controls
• Machine center and turning center
• Coordinate measuring machines

Components of FMS
Basic components of FMS are:
• 1
...
Automated Material Handling and Storage system
...
Computer Control System
1
...
Flexible manufacturing systems are being
designed with other type of processing equipments including inspection stations, assembly works and sheet
metal presses
...


Components of FMS
2
...
systems are used to transport work parts and
subassembly parts between the processing stations, sometimes
incorporating storage into function
...
Computer Control System: It is used to coordinate the activities of the
processing stations and the material handling system in the FMS
...
The initial phase of FMS planning must consider the parts that will be produced
by the system
...
They include the
following:
1
...
In effect, the part family to be processed on the FMS
must be defined
...

The term product commonality refers to different components used on the same product
...
Processing requirements:- The types of parts and their processing requirements determine the
types of processing equipment that will be used in the system
...

3
...

4
...
Production volume is also a factor in selecting the most
appropriate type of material handling equipment for the system
...
When the links in the tree are implemented
by a computer network, then that hierarchical control system is also a form of networked control
system
...
Referring to the diagram;
• Level 0 contains the field devices such as flow and temperature sensors, and final control
elements, such as control valves
...

• Level 2 contains the supervisory computers, which collate information from processor nodes on
the system, and provide the operator control screens
...


Supervisory computer control

Supervisory computer control
• Supervisory control represents a higher level of control than CNC, PLCs, and other
automated processing equipment
...
By
contrast, supervisory control is superimposed on these process level control
systems
...

• The objectives of supervisory control are motivated by economic considerations
...


Machining center
• Machining centers are classified as vertical, horizontal, or universal
...
A vertical machining
center has its spindle on a vertical axis relative to the worktable, and a horizontal
machining center has its spindle on a horizontal axis
...
A vertical machining center (VMC) is typically used
for flat work that requires tool access from the top
...

• A horizontal machining center (HMC) is used for cube-shaped parts where tool
access can best be achieved on the sides of the cube
...
Airfoil shapes and other curvilinear geometries often require the capabilities
of a UMC
...
Typical features include:
• Automatic tool-changer
...
The tools are contained in a
tool storage unit that is integrated with the machine tool
...
Capacities of the tool storage unit commonly range
from 16 to 80 cutting tools
...
Many horizontal and universal machining
centers have the capability to orient the work part relative to the spindle
...
The table can be oriented at any angle about a vertical axis to
permit the cutting tool to access almost the entire surface of the part in a
single setup
...
Machining centers are often equipped with two
(or more) separate pallets that can be presented to the cutting tool using
an automatic pallet changer
...
In this safe location, the operator can unload the finished
part from the prior cycle and then fixture the raw work part for the next
cycle
...
The success of NC machining centers motivated the development of NC
turning centers
...

• The use of multiple cutting tools is enabled by one or more tool turrets, each turret
holding typically 6 to 12 tools for turning and drilling
...

• Other advanced features of turning centers include
(1) work part gaging (checking key dimensions after machining),
(2) tool monitoring (sensing when the tools are worn),
(3) automatic tool changing of worn tools,
(4) automatic part changing at the completion of the work cycle
...
In
past, deburring was purely a manual, repetitive process that was highly
labor intensive
...

• Presently various high-tech methods have emerged or have been perfected
to deal with the problem of automating and reducing the manual effort
required for burr removal
...
Mechanical
2
...
Thermal energy
4
...

In this method deburring is done by supplying rotational power to the wire brush or grinding
wheel which is held at the end effector of the robot, while the robot’s articulated arm
positions the deburring tool in all its proper positions to remove the burrs
...
Parts systematically
enter a large bowl container filled with ceramic pebbles commonly referred to as media
...
The size of the ceramic media
can vary depending upon the type, size and material of the parts to be deburred
...


Deburring
3
...
The parts to be deburred are
sealed in a chamber, which is pressurized with a mixture of combustible gas and oxygen
...
This gaseous mixture is then ignited by a spark
plug, which creates an instant burst of intense heat, and burrs, because of their high ratio
of surface to area mass, burst into flames
...

4 Electrochemical Deburring
• Electrochemical deburring machines can deburr contour parts through an
electrochemical reaction that dissolves metal from a work piece into an electrolyte
solution
...
The electrode is connected to the negative, and the
work piece to the positive terminalof a D
...
source
...
Thus electrochemical reaction takes place and burrs
are removed
...


Cleaning (Wash Stations)
WASH STATIONS
• Wash stations play an important role in the flexible manufacturing system
...
Wash stations
can accommodate a variety of different parts as long as the parts can fit within the required size limitations
...
They are
1) Batch type wash stations
2) In-line type wash station
1 Batch Type Wash Stations
• The batch washers handle work pieces weighing thousands of pounds and as large as 72-inch cube
...

2 In-line Type Wash Stations
• In-line washers are used for high-volume production where high and rapid production rate is required
...
Separate roller conveyors can be added at the load-unload sections for interfacing
...


Coordinate Measuring Machine (CMM)

Coordinate Measuring Machine (CMM)
• Coordinate metrology is concerned with measuring the actual shape and dimensions of an object and
comparing these results with the desired shape and dimensions, as might be specified on a part drawing
...

• A coordinate measuring machine (CMM) is an electromechanical system designed to perform coordinate
metrology
...
The x, y, and z coordinates of the probe can be accurately and precisely recorded to obtain
dimensional data about the part geometry
...

• In addition, many CMMs include the following:
• Drive system and control unit to move each of the three axes
• Digital computer system with application software

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