Oscillating Conveyor System

Selection of vibratory conveyor:

The oscillating motion of the trough is achieved via specially designed inclined arms and an eccentric shaft driven by a motor through V-belts. The eccentric shaft is mounted on anti friction bearings and has V-pulleys at both ends with weights on them to counteract the unbalancing force. The rotation of the eccentric shaft provides a forward and backward motion to a connecting arm attached to the trough through a rubberized pin. The trough motion is predominantly horizontal with some vertical component, which causes it to oscillate with a pattern conductive to conveying material. A retaining spring assembly at the back of the trough absorbs shock load. All components including drive motor are mounted on a rigidly constructed base frame.

Advantages:

· Hot and abrasive materials can be handled

· Cooling, drying and de-watering operation can be done during transport

· Scalping, screening or picking can be done

· Units can be covered and made dust tight

· Simple construction and low head room

· Can be made leak proof

Disadvantages:

· Relatively short length of conveying ( about 50m Maximum)

· Limited capacity, about 350 tons per hour for length of conveying of 30 m.

· Some degradation of material takes place.

Applications:

Vibratory conveyors find wide spread application in the transportation of dusty, hot, toxic, and chemically aggressive bulk material through a closed trough or pipe in chemical, metallurgical, mining industries and manufacturing of building materials.

Vibratory conveyors are also employed for transportation of steel chips in machine shop, hot knocked out sand, wastes and small castings in foundry shop. Vibratory feeders are also in use for delivery of small machine parts like screws, rivets etc.

Sticky materials like wet clay or sand are unsuitable for vibratory conveyors. In handling finely pulverized materials, like cement etc., the performance of such conveyors are reported to be poor.

Vibratory conveyors are hardly employed for handling common bulk loads, such as sand, gravel, coal etc as the same can be done more efficiency by belt conveyors.

FMEA

Failure Mode – A particular way in which an item fails, independent of the reason for failure.

 Failure Mode and Effects Analysis (FMEA) – A procedure by which each credible failure mode of each item from a low indenture level to the highest is analyzed to determine the effects on the system and to classify each potential failure mode in accordance with the severity of its effect.

Indenture Levels – The hierarchy of hardware levels from the part to the component to the subsystem to the system, etc.

Redundancy – More than one independent means of performing a function.  There are different kinds of redundancy, including:
(1) Operational – Redundant items, all of which are energized during the operating cycle; includes load-sharing, wherein redundant items are connected in a manner such that upon failure of one item, the other will continue to perform the function.  It is not necessary to switch out the failed item or switch in the redundant one.

            (2) Standby – Items that are inoperative (have no power applied) until they are switched in upon failure of the primary item.

            (3) Like Redundancy – Identical items performing the same function.

            (4) Unlike Redundancy – Non identical items performing the same function

THE FMEA PROCESS

• Define the system to be analyzed.  A complete system definition includes identification of internal and interface functions, expected performance at all indenture levels, system restraints, and failure definitions.  Also state systems and mission phases not analyzed giving rationale for the omissions.

• Indicate the depth of the analysis by identifying the indenture level at which the analysis is begun.

• Identify specific design requirements that are to be verified by the FMEA.

• Define ground rules and assumptions on which the analysis is based.  Identify mission phases to be analyzed and the status of equipment during each mission phase.

• Obtain or construct functional and reliability block diagrams indicating interrelationships of functional groups, system operation, independent data channels, and backup or workaround features of the system.

• Identify failure modes, effects, failure detection and workaround features and other pertinent information on the worksheet.

• Evaluate the severity of each failure effect in accordance with the prescribed severity categories.

FMEA Flow Diagram:

History:

The FMECA was originally developed by the National Aeronautics and Space Administration (NASA) to improve and verify the reliability of space program hardware.

FMECA Flow Diagram: ( Failure Mode, Effects and Criticality Analysis )

Criticality Analysis Flow:

Who is the Team ?

 

Areas to be represented are:

• Quality

• Logistics

• Engineering

• Purchasing

• Manufacturing

• Sales

• Tooling

• Marketing

• Customer

• Supplier

MATERIAL HANDLING

Bases on Design features and operational characteristics, material handling equipment may be broadly classified as:

Hoisting Equipment’s:

It constitute a group of equipment which are employed mainly for lifting or lowering of unit load or piece goods in batches. This group of equipment’s can be further sub classified into:

1. Pure Hoisting Machineries

• Jack
• Winches
• Hand Hoists
• Pulley Blocks

2. Cranes

• EOT Crane
• Jib Crane
• Cantilever Crane

3. Elevators

• Lift
• Bucket Elevators

Conveying Equipment’s:

It comprises of a number of equipment which are employed for handling principally bulk load (occasionally piece goods or unit load may also be handled) in continuous flow. Such machines do not have separate lifting or lowering gear. This group of equipment also can have further sub classifications as:

1. Belt Conveyor

2. Hydraulic Conveyor

3. Pneumatic Conveyor

4. Apron Conveyor

5. Screw Conveyor

6. Flight Conveyor

Surface/ Overhead Equipment’s:

These are the group of equipment’s which are employed for handling unit load or bulk load in batches on a horizontal surface. This group of equipment may be further sub classified into:

1. Truck and Lorries

2. Railway Cars and Wagons

3. Fork Lifts

4. Overhead mono-rail / Equipment

5. Scrapers and Skidders

Types of Material Handling Equipment Loads:

It usually classified into:

1. Unit Load

2. Bulk Load

Unit Load:

Unit loads are those which are counted by numbers or units. A component of a machine, a complete machine, a structural element, a beam, a girder, building block are some examples of unit load.

Sometimes certain quantities of free flowing materials can be placed in a container and can be handled as unit load. Hoisting equipment are primarily used for handling unit load. Unit loads are usually specified by it’s weight.

Bulk Load:

When the load is in the form of particles or lumps of homogeneous materials or powder like materials, which can not be counted by numbers, it is called as “Bulk load”.

Examples are:

Sand, Cement, Coal, Mineral, Stone, Clay etc.,

A bulk material may be classified by it’s:

1. Bulk Density

2. Lump-Size

3. Flowability

4. Abrasiveness

5. Miscellaneous Characteristics

FAILURE ANALYSIS

• Why ?

As the standards of our industry rise due to increasing globalization and competition, there is an ever growing need for consistency and reliability. Breakdown of any unit, system or equipment is an avoidable and costly occurrence and must be prevented or minimized. Analysis of such failures becomes a resourceful and affordable tool in addressing such unwanted occurrences.

To establish whether the cause of component failure lay on:

a) Service conditions
b) Design considerations
c) Material and its specification
d) Improper processing and assembly procedures or
e)  Combinations of these.

Only the real “Root cause” can ensure the effectiveness of corrective and preventive actions and avoid recurrence of failure.

• Stages Of Failure Analysis

1. Understanding and assimilation of background data and selection of samples.
2. Examination and documentation of the failed part by the following

1. Visual examination of parts, location (if necessary) and relevant photographs as well.

2.  Non destructive testing by means of Radiography, Dye      penetrant, Magnetic particle testing etc.

3. Mechanical Testing for various physical properties.

3. Vital specimens are selected, classified, and subjected to:

1. Macroscopic examination and analysis. This involves examining the fracture surfaces, secondary cracks, deposits and other such elements
2. Microscopic examination and analysis of fracture surface (by Scanning Electron Microscopy, if required).

4. Chemical analysis of material for conformation to specifications.

5. Chemical analysis of corrosion products, deposits, contaminants etc.

6. The actual state of the failed part and the failure mode are established.

7.  Fracture mechanics study if found necessary.

8. A simulation of the identical working environment to determine if any external      factors have contributed to the failure

9. Conclusions are determined after compiling all evidences and analysis and       then the report is generated.
10. Follow-up recommendations are also provided.