Factory Information System

Machine monitoring

What does the Machine Monitoring module do?

A machine monitoring system uses sensors on a machine to measure its output, cycle time, and downtime automatically.

It relates this information to the part which the machine is making, and the operator who is running the machine, in order to analyse machine performance, and highlight waste of materials and machine time.

The information it produces is accurate and it is up-to-date. Problems can be identified as they happen and corrective action taken immediately.

By measuring accurately the activity of your machines, a machine monitoring system gives you real control of your production process. You can use this information to reduce waste and increase the capacity of your plant using existing resources.

Is it suitable for my business?

The Machine Monitoring module is suitable for a business using any type of machine with a reasonably constant cycle time. This definition encompasses all fully automatic and most semi-automatic machines. Machine monitoring will not work on manual machines such as toolroom lathes and milling machines.

Most of our customers make parts in medium to high volumes, but some use machine monitoring because their machines have a very high capital cost and they wish to ensure that they are earning their keep.

We have successfully monitored all the following types of machine.
  • Automatic lathes
  • CNC lathes
  • CNC machining centres
  • Cold heading machines
  • Presses
  • Transfer lines
  • Tapping machines
  • Thread rolling machines.
  • Diecasting machines
  • Injection moulding machines
  • Compression moulding machines
  • Thermoforming machines
  • Assembly machines
  • Packing and filling lines
  • Tube bending machines

What equipment do I need?

Monitoring unit

A monitoring unit is fitted to each machine.

A monitoring unit is a small computer with a single line display and a keypad. It runs software which uses the signals from the machine to perform the following functions.
  • Count parts made.
  • Measure the cycle time of the machine.
  • Detect when the machine begins to produce parts.
  • Detect when the machine stops producing parts.
The monitoring unit contains a clock which allows it to record the exact time at which the machine starts and stops.

When the machine stops, the monitoring unit prompts the operator to use the keypad to enter a reason for the downtime. In some circumstances it may be possible to provide additional signals from the machine to determine the cause of downtime automatically.

Function keys on the keypad allow the operator to display relevant information at the machine. Such information might include:
  • Quantity made and quantity required on this job.
  • The quantity made during this shift and the previous shift.
  • Actual cycle time and planned cycle time for this job.
  • Reason for and duration of the current or most recent downtime.
  • The total downtime during this shift and the previous shift.
  • The efficiency of the machine during this shift.
A function may be set up to allow a number of scrap parts to be entered by the operator.
Job changes can be recorded by pressing a job change key on the monitoring unit, or by wiping a bar-code on works order documentation. In both cases the monitoring unit can then interact with the central computer to obtain details of the new job.

The display of this information at the machine helps operators to avoid over- and under- production, and allows them to ensure that the machine is running at the planned cycle time.

The monitoring unit contains a relay output which can be used to stop the machine or prevent it being started.

Many customers now have the monitoring unit interlocked with the machine so that the machine cannot be started until a reason for the downtime has been entered using the keypad.

The monitoring unit initially stores the information it has collected in its own battery-backed memory. This information is transferred to the host computer when required for a report. The use of local storage in the monitoring unit makes the system tolerant to faults in the host computer or cabling system.

The monitoring units are connected to a host computer by a single cable which leaves the host computer, visits each monitoring unit in turn, and returns to the host computer, thus forming a ring. This connection allows information to be transferred in both directions between monitoring units and the host computer.

PC to store and analyse information

The information collected by the monitoring units is collected by a host computer. This is a single IBM compatible personal computer, or a network of such computers. The information from the monitoring units is first safely stored onto disc, and then used to compile various reports.

Software to produce reports and manage system

The reports produced by the system fall into four main categories.

Current status of machines

These reports show the current status of one or a group of machines. They are refreshed automatically so that you can always see which machines are running, which are stopped, and why they are stopped. This information can be displayed as a plan of your factory.

Downtime analysis

These reports provide summaries of downtime for a machine or a group of machines over any time period. The system includes predefined periods such as a shift, day, week, and month. You can start by displaying a summary report for a group of machines and then 'drill down' into the data in increasing detail to find out the cause of downtime and poor performance.

Job analysis

These reports allow you to examine the performance of a particular job or all the jobs for one part on one machine or a group of machines. You can use them to check the performance of different machines making the same part, to find jobs which result in low machine performance, and to cost jobs accurately. The system allows you to enter the earnings for each part and thus will produce reports showing factory earnings in money terms.

Operator Analysis

These reports allow you to examine the performance of a machine while it was under the control of a particular operator. The system will produce operator time-sheets showing how an operators time was used, and the performance of the machines he was using. This can form the basis of individual or group bonus schemes. It will show who worked on a particular machine or job, thus enabling responsibility to be established for scrap or for good performance.

What are the benefits of a machine monitoring system?

Measurement gives control

You cannot control what you cannot measure.

Most companies try to control their production with minimal or out-of-date information on what is actually happening on the shop-floor.

A machine monitoring system gives you fast and accurate measurement of what is happening on your shop-floor. This information puts you in real control of your factory.

Accurate parts counting

The system counts parts accurately. It allows machine operators and production managers to compare the quantity made with the quantity required at any time. This avoids under-production which leads to customer dissatisfaction, and over-production which wastes material and ties up capital in unwanted stock.

Constant monitoring of cycle times

The system continuously monitors the cycle time of the machine. It allows machine operators to set the machine to the planned cycle time, and see immediately the effect on cycle time of any adjustments they have made. On mechanically controlled machines such as Wickmans and single spindles, a discrepancy between the planned and actual cycle time may indicate an incorrect set up, or may indicate a machine fault, such as a slipping clutch. On CNC machines the operator usually has much more control over the cycle time of the machine and may have slowed down the speeds and feeds without good reason.

In both these cases the system allows you to spot these discrepancies and eliminate them. Small increases in a short cycle time soon accumulate into many lost components.

Record of duration and reasons for downtime

Accurate recording of the duration of and reasons for downtime allow you to reduce or eliminate it. This can often be achieved by simple measures such as ensuring that machines run immediately at the start of a shift, and are not shut off until the end of the shift. Analysis of downtime often shows failures in the services to your machines, such as material issue, tooling, and maintenance. A machine monitoring system eliminates arguments about the causes of downtime and forces everyone to contribute to its reduction.

Record of job changes

A record of job changes allows you to follow jobs and work-in-progress around your factory. The system records machine performance against each job, which enables you to identify jobs which are unprofitable, and conversely those which have particularly low costs.

Record of operator changes

If you operate a bonus scheme, a machine monitoring system will eliminate most of the time required to perform bonus calculations. Bonus information can be made available to operators during each shift so that they know what they have to do to achieve their desired level of bonus.

Instant calculation of OEE

The system calculates Overall Equipment Effectiveness (OEE) immediately for any time period, and for any job. It separates out the three elements of OEE, namely Availability, Performance and Quality. Perhaps more importantly it gives you the information you need to increase your OEE and thus to get more production from the same inputs.

Increase capacity without buying new machines.

Armed with the reasons why your machine utilisation and efficiency are not as high as they should be you can set about eliminating downtime and improving cycle times. You will often find that services to machines, such as stores, toolroom, and maintenance are the cause of much of your downtime. Armed with accurate information you can tackle these problems.

The result of this is that you can increase the capacity available from your machines without the need to buy new machines or take on extra staff. An increase of 5% in the utilisation of 20 machines is equivalent to buying a new machine, but does not require extra floor space, operators, or the capital to buy the machine. Such an improvement in utilisation can often be achieved simply by ensuring that machines are run for the whole of a shift, and that material and tooling are available when they are required.

Investment appraisal

In addition to its use for daily production management, a machine monitoring system gives you vital information for investment appraisal and machine replacement decisions.

Identify worn-out machines

Any factory has a folklore about certain jobs which can and cannot be run on certain machines. The information from a machine monitoring system gives you the facts you need to prove or disprove such theories.

You can carry out comparative studies of breakdowns on your machines over a long period to decide when a machine should be replaced or reconditioned.

Check that new machines are meeting specification

New machines are often sold on the basis that they will meet strict performance targets for cycle time, utilisation and availability.

A machine monitoring system allows you to check that the machine is meeting the targets you were promised, and allows problems to be identified if targets are not being met. Since the system measures machine performance directly it is fair to both you and your machine supplier.

 

©2011 Rhombus Systems Limited, Sumpter House, 8 Station Road, Histon, Cambridge CB24 9LQ