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How to calculate OEE for multiple machines

Overall Equipment Effectiveness (OEE) continues to gain acceptance as an effective method to measure production floor performance. Capturing and recording accurate production floor information is critical for producing reliable OEE Reports.

OEE-Benchmark-Survey

A number of production floors are utilizing manual methods of data collection for producing OEE report. This approach leaves room for both inconsistencies and inaccuracies. With manual data collection, there is usually a second step of manually compiling the data. This is most commonly accomplished by entering in the information into spreadsheets. This manual compilation step also leaves room for both inconsistencies and inaccuracies.

Another disadvantage to manually collecting data for your OEE reports, like with many maintenance and production improvement plans, is sustainability. The more task intensive an improvement plan is, the more likely priorities will change and the OEE initiative will fade away. With an automated data collection system, sustainability is no longer an issue. Once in place the automated OEE reporting stays in place and you need only act on the results.

There are cost effective automated data collection alternatives to manual data collection that significantly improve the accuracy of OEE reports. Automated capturing and recording of “Availability Information” will be covered in this article. Future articles will address the automated data collection of Performance Rate and Quality Rate.

OEE

OEE = Availability X Performance Rate X Quality Rate

Availability – Percent of scheduled production (to measure reliability) or calendar hours 24/7/365 (to measure equipment utilization) or equipment or line status (to measure ability to produce), that equipment or a production line is available for production.

Note: Measures the percent of time that the equipment can be used (usually total hours of 24-7-365), divided by the equipment uptime (actual production).

Performance Rate – Percent of parts produced per time frame, of maximum rate OEM rated production speed at. If OEM specification is not available, use best known production rate or a standard production rate can be established.

Note: Performance efficiency is the percentage of available time that the equipment is producing product at its theoretical speed for individual products. It measures speed losses. (i.e. inefficient batching, machine jams)

Quality Rate – Percent of good sellable parts out of total parts produced per time frame.

Note: Determining the percent of the total output that is good. (i.e. all products including production, engineering, rework and scrap.)

Example: 50% Availability (0.5) X 70% Performance Rate (0.7) X 20% Quality Reject Rate (results in 80%(0.8) acceptable) =30%OEE (Please see DowntimeCentral.com/OEE_TEEP.htm for a free online calculator to practice with.)

Defining What Is Availability

One of the first steps in initiating OEE reporting is defining the parameters for the elements of OEE for the individual piece of equipment, production line or the entire factory. That is clearly defining, documenting and communicating why a piece of a piece of equipment or a production area is unavailable for producing product.

There are three basic approaches to defining availability. The approaches are the percent of scheduled production, calendar hours, and equipment or line status. The schedule production approach defines availability by the production schedule for a piece of equipment, a cell or an entire production line. The calendar hours defines availability as the total time available to produce product which is usually 7-24-365. The equipment or line status approach defines availability in terms that production line or piece of equipment is in a state to produce product. All three approaches are valid approaches. The percent of scheduled production and calendar hours provide a broad view of availability while the line status approach is a much more defined view.

Some examples to consider as causes for unavailability is power to piece of equipment or does the production station have personnel in place. The above two causes may not be enough to define the reason for unavailability. You may need to add data inputs recording if there was materials in place or the status of the infrastructure support (such as air pressure for air driven tools and equipment) as monitoring points to determine if a piece of equipment, a cell or an production line is available to produce a product. Availability must be defined for each area or piece of equipment that will have OEE reports. In some of the instances there will be more than one element that needs to be monitored to determine if that piece of equipment or area is considered available.

Automated Data Collection

Setting a goal of capturing availability status information with no manual data collection or manual compilation for OEE calculations is the first step in improving both the accuracy of OEE reports as wells as reducing the cost to produce the reports. Start with defining what affects availability for various areas of a production facility. Identify the specific data collection points that will affect availability for a given area or unit of equipment. In many cases there are data collection points already in place. For those monitoring points, you need only to retrieve the existing data. In other instances, a data collection monitoring device will need to be installed.

For installing new data collection points, there are available a variety of inexpensive sensors that once installed, can capture the measurement of numerous parameters. These sensors can detect flow rate, weight, quantity, motion activity, phases of electrical power as wells as many other items. The sensors usually come with normally open or normally closed switch contacts. These switch contacts will serve as the data collection points for automated data collection.

Using sensors with switch contact outputs for most monitoring situations are probably the easiest approach for capturing availability data. To monitor equipment starting with power switches and other functions of equipment, it is often the case of adding an extra set of inexpensive contacts to an existing switch on the equipment.

There are other means to capture activity status information including embedded equipment control software and equipment monitoring software that can capture the parameters for availability. What must be factored into the monitoring approach is that each monitoring point must include a time and date stamp.

The data collected from the monitoring points must be transmitted to a database for data retention and reporting. The database that captures and records the status information can be a commonly available P/C database packages such as Microsoft Access®. It is critical that all data points recorded must include time, date and location stamps to support the development of OEE reports. Database report writers can be used to extract the information to produce OEE reports.

In addition to custom in house database systems, there are available integrated data collection systems with application software packages with complete OEE Reports. These systems and reporting can be tailored to each individual facility’s requirements.

The Wireless Connection

The implementation of the wireless LAN or other wireless technologies to capture and transmit availability data greatly enhances the timeliness, utilization and flexibility of the data collection system. Hard wired systems over time, limit the functionality of a data collection system. In the past wireless technologies did not provide the high level of reliability that is required for factories, leaving the hard wired systems as the only alternative. That is no longer true especially with the introduction of the wireless LAN 802.11g standard and advanced 900 MHz technology. Wireless data collection and transmission systems provides for easy reconfigurations of changing production floor layouts or changing production flow activity. A number of off-the-shelf production floor wireless data collection systems are available for use on the production floor.

Cost Justification

The implementation of an automated data collection system with an integrated database provides immediate financial returns. The labor cost associated with manual data collection on production lines by production personnel and the manual compilation of the data to calculate OEE are eliminated with an automated system. The accuracy and integrity of the source data is significant improved. With more accurate OEE reports you will make better financially feasible decisions that will result in even greater savings. The timeliness of the OEE reports themselves are also significantly improved with automated data collections. In most cases, the OEE Reports are available for review the same date as the final element of information is captured.

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April 16, 2018 Posted by | Lean, maintenance, manufacturing | , , , , , | Leave a comment

Engineering Funny Connections – YouTube

Just added #Funny #HVAC to our Engineering Funny Connections – YouTube.

Though you all might like and share. You can learn and laugh at the same time!

June 26, 2013 Posted by | Education, Electrical, engineering, Humor, Lean, maintenance, manufacturing | , , , , , , , , | Leave a comment

Working Relationship with Robots Will Lead to New Opportunities

The relationship between man and robots is even more important for those in industrial manufacturing to understand. This post mostly to with industrial robots

Robots in America

Implementing automation allows companies to be more — to be more productive, to be more globally competitive, to be more efficient. Reflecting on the history of technology and economy, we know that automation is a dynamic force in industry. Kevin Kelly predicts a future of automation that will surprise us — technology that performs jobs we never knew needed doing and that gives us opportunities we are just beginning to understand.

Better Than Human: Why Robots Will — And Must — Take Our Jobs
by Kevin Kelly

That may be true of making stuff, but a lot of jobs left in the world for humans are service jobs. I ask Brooks to walk with me through a local McDonald’s and point out the jobs that his kind of robots can replace. He demurs and suggests it might be 30 years before robots will cook for us. “In a fast food…

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February 10, 2013 Posted by | engineering, manufacturing, PLC, Skill Shortage | , , , , , | Leave a comment

Hope- 5 Positive Earnest Expectations For 2013

…as long as we can make it through the next two months without US House of Rep screwing it up.

Speaking of Precision Blog

Had a great discussion with a colleague about “Hope.” He defined  hope as being “earnest expectations”-  as opposed to all the nebulous, touchy-feeley stuff that most people seem to think it is.

I considered what he said, and offerred, that to me,  hope is more than just earnest expectations.

Hope is Positive Earnest Expectations!

Here are my 5 Positive Earnest Expectations for 2013:

Automotive market will continue to strengthen. 

VehicleSalesLongFeb2012

When I worked at a steel barmill, it was certain knowledge that automotive was the most important driver of bar steel sales. “No one would build a bar mill for steel if it wasn’t for automotive.” Said Everyone. To. The New Guy. (Me.) We see estimates of a 15 million auto sales for 2013. That may be a little high, but if housing continues to strengthen too, well, tradesmen will need pickup trucks and vans. And THAT could be a boost to…

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January 11, 2013 Posted by | manufacturing, Skill Shortage | , , , | Leave a comment

Underpaying workers is not a “Skills Gap”. | LinkedIn

A great discussion going on here where both the Root Cause is also the quickest Solution as well as the Long Term Fix. Why not join in the discussion? Click…

Underpaying workers is not a “Skills Gap”. | LinkedIn.

January 9, 2013 Posted by | Skill Shortage | , , , , , , | Leave a comment

Industrial Technology Training Shirts Mugs etc.

Industrial Technology Training Shirts Mugs etc..

We started off with the most popular (and funny) industry sayings as surveyed by maintenance, electricians, mechanics, millwrights, engineers and manufacturing in general.

1 of many industrial sayings

November 22, 2012 Posted by | engineering, maintenance, manufacturing, Uncategorized | , , , , , , , , | Leave a comment

Best Practices for PLC Programming

Best practices PLC programming

PLC Programming

September 27, 2012 Posted by | Uncategorized | , , , , , | Leave a comment

Autonomous Maintenance Level 2

Autonomous Maintenance Level 2

Time to bring your plant operators up to Autonomous maintenance level 2. See http://www.bin95.com/reliability_training.htm for phase II of this Lean TPM principle.

May 26, 2012 Posted by | Lean, maintenance, manufacturing | , , , , , | 1 Comment

Free Online PLC Training Interactives

Allen Bradley Data File training

Click to Learn

A set of 4 free online interactive memory tools to learn and memorize the Allen Bradley Data Tables. Totally free, no registration or email required. Just use and share with others. The decision to make more training tools on other topics will depend on how popular these are.  So if you like the tools, be sure to share with as many others as you can. also there is a comment area where you can recommend other topics you would like to see.

(And thanks to our January PLC training graduates who requested we make a memory tool for PLC Data Types.)

January 21, 2012 Posted by | Electrical, engineering, manufacturing, PLC | , , , , , , , , , , , | 4 Comments

Maintenance Management of your company’s PLC

(Programmable Logic Controller).

By Don Fitchett

(This article also featured in November 15, 2007 Chemical Engineering Magazine)

  • What is a PLC?
  • How many PLCs is your bottom line depending on?
  • Do you have an up to date list of all PLC model types, part availability, program copies, and details for your company?
  • Do you have at least one trained person per shift, to maintain and troubleshoot your plant PLCs?
  • Does your maintenance personnel work with PLCs following written company or corporate policy, and procedures?

If you could not answer with confidence or you answered ‘No’ to any of the above questions, you need to read this article on maintenance management of PLCs. Why? Because the PLCs (Programmable Logic Controllers) are the brains of your operation. When the PLC is not functioning properly, lines shut down, plants shutdown, even city bridges and water stations could cease to operate. Thousands to millions could be lost by one little PLC in an electrical panel that you never even knew existed. But most importantly, damage to machine and personnel could result from improper maintenance management of your company’s PLCs.

What is a PLC?

First I’d like to explain in the most  non-technical terms possible, What a PLC is. As this article is not just for the maintenance technician, but for maintenance managers, plant managers and corporate managers. A PLC (Programmable Logic Controller) is the type of computer that controls most machines today. The PLC is used to control AND to troubleshoot the machine. The PLC is the brain of the machine. Without it, the machine is dead. The maintenance technicians we train, are the brain surgeons. That is how I explain it to my doctor any way. (His mouth drops open, “… you train brain surgeons?”)

Important Note: Just as a doctor asks the patient questions to figure out what is wrong, a maintenance technician asks the PLC questions to troubleshoot the machine. The maintenance technician uses a laptop computer to see what conditions have to be met  in order for the PLC to cause an action to occur (like turn a motor on). In a reliable maintenance management environment, the maintenance technician will be using the PLC as a troubleshooting tool to reduce downtime.

A little more detailed definition of a PLC: A programmable controller is a small industrial strength computer used to control real world actions, based on its program and real world sensors. The PLC replaces thousands of relays that were in older electrical panels, and allows the maintenance technician to change the way a machine works without having to do any wiring. The program is typically in ladder logic, which is similar to the wiring schematics maintenance electricians are already accustomed to working with. Inputs to a PLC can be switches, sensors, bar codes, machine operator data, etc. Outputs from the PLC can be motors, air solenoids, indicator lights, etc.

How many PLCs is your bottom line depending on?

My company has had an ongoing PLC related global maintenance survey since the year 2000. The majority of the participants back in 2001, reported 3-6 PLCs in their facility, that they know of. Granted most participants are managers and don’t open electrical panels much, but many of the participants are from fortune 500 companies having hundreds of employees. The odds are most of them have 12-30 PLCs in their facilities. Currently the average is 6-9 reported, so the good news is the industry as a whole is becoming more PLC aware.

It is common to only learn about a PLC once the machine is down and the clock is ticking at a thousand dollars an hour, or more. Unfortunately, it is also common that after the fire is out, it’s on to the next fire, without fully learning what can be done to avoid these costly downtimes in the future, and in other similar machines in a company or corporation.

Some older electrical panels may only have relays in them, but most machines are controlled by a PLC. A bottleneck machine in your facility may have a PLC. Most plant air compressors have a PLC. How much would it cost if the bottleneck or plant air shut down a line, a section of your facility, or even the entire plant?

Do you have an up to date list of all PLC model types, part availability, program copies and details for your company?

The first step to take is to perform a PLC audit. Open every electrical panel, and write down the PLC brand, model, and other pertinent information. Then go the next two steps. Analyze the audit information and risk, then act on that analysis. To help you out, I want to share with you our company PLC audit form.

Collected Information Recommended Action
Machine or Area Name Ex: warehouse conveyor, pump station 3,Strapper 2, Line 7, Traffic signal west main, etc.
PLC Program Name Ex: 1789GAA1, P3, Strap2, 5872443, WestMainTL, etc.
Network Node Address No two addresses will be the same. Ex: 2, 3, 17, 21
Network Name Common to be same as Program name, but not mandatory.
PLC Brand Ex: Allen Bradley, Siemens, Schneider, Mitsubishi, DirectSoft, Omron
PLC Model Number Ex: PLC-5/25, SLC-504, SIMATIC S5, MELSEC FX1N, DL 405
Is Spare Available Yes on shelf, or only in less critical machines or no
Date Program Last Backed Up Make program backups part of your semiannual PM program
Discriptored Copy of program available Without discriptored copy of program, troubleshooting and downtime are greatly increased.
Does PLC have EEPROM Or other method of storing backup program in a chip on PLC
Last date Program Changed Remember to log when outside consultants or OEM make  program changes too.
Last date EEPROM Burned Should be saved to EEPROM (Burned) after every successful program change.
Date battery last changed See manufacturer’s data for recommended change frequency.
Other information you may need Might be facility location when corporate HQ is using this form.

Once you have collected the basic information in your Plant wide and/or corporate audit, you need to analyze the information to develop an action plan based on risk analysis. In the risk analysis, bottlenecks and other factors will help you assess priorities. Starting with the highest priority PLC, you will need to ask more important questions.

o        Do we have the most common spares for the PLC?

o        Is the OEM (Original Equipment Manufacturer) available 24/7? Or even in business any more?

o        Do we have a back up copy of the PLC program?

o        Does our program copy have descriptions so we can work with it reliably and efficiently?

o        Do we have the software needed to view the PLC program? Are our maintenance personnel trained on that PLC brand?

These are some of the questions our managers must ask, to avoid unnecessary risk and to insure reliability.

Do you have at least one trained person per shift to maintain and troubleshoot your plant PLCs?

Is your maintenance staff trained on the PLC? (Silly to squander over a couple thousand in maintenance training when the lack of PLC knowledge could cost you 10 thousand an hour. … or worse. I can give you a couple good reasons why you should have at least one trained person per shift, to work reliably with PLCs. You do not want to see greater downtime on off shifts because the knowledge base is on day shift only. Also with all the baby boomers (our core knowledge base in the industry) about to retire, it is not smart management to place all your eggs in one basket.

Then the question should be asked, what should we look for in training. Well I have been training individuals for over a decade and could easily write another article on just PLC training alone. I can tell you here, that you should seek training with two primary objectives.

1.      The training you decide on, should stress working with PLCs in a Safe and Reliable way. (not just textbook knowledge or self learned knowledge)

2.      Secondly, the training should be actually centered around the PLC products you are using or plan to use in your facility.

I feel the two criteria above are the most important. Some other good ideas to get more out of your PLC training investment would be to get hands on training using the actual PLC programs and software the maintenance technician will be working with in the facility. Insure your personnel have the software, equipment and encouragement to continue with self education. PLC Training CBT (Computer Based Training) CDs are a great way for employees to follow up 6 months after the initial training. Some other ideas you could do is to provide them with simulation software and/or a spare PLC off the shelf to practice with.

Does your maintenance personnel work with PLCs following written company or corporate policy and procedures?

It seems that in our industrial culture, if policy and procedures are not written and enforced, we eventually stray back to the old unreliable ways. I have reviewed many policy and procedures as well as books on the topic matter and hardly ever see maintenance management of the PLCs included. It amazes me how an organization can write guidelines for what they believe is the health of the entire organization’s body, and leave out the brain (the PLC :>). Once again, a complete PLC policy and procedure manual is out of the scope of this article. However, I will donate a few random items below to get you started.

1.      Write PLC policies and procedures into your existing maintenance policy and procedures. (SOP)

2.      All personnel working with PLCs will be trained on that PLC equipment.

3.      Backup copies of the PLC programs will be made every 6 months regardless of change status.

4.      If a PLC program has been changed …

a.      It will be documented in the software copy, in the printed copy and in the CMMS program.

b.      Copies of the PLC program will be stored on a media more reliable than floppy disk (CD, USB, etc.).

c.      Multiple copies will be stored on laptop, maintenance manager’s office and off site (corporate).

d.      If available, EEPROM will be updated with new changed program.

i.     If outside vendor changes, a-d will be performed by maintenance personnel

5.      Future equipment purchases …

a.      A common PLC brand in all equipment will be sought out (Standardization of PLC types)

b.      OEM will be required to provide a descriptor copy of PLC programs in the customer’s native language.

c.      All PLC 110v control voltage will have a line filter on it.

d.      All PLCs will have the backup EEPROM option for zero downtime in some failure modes.

6.      Forcing inputs and outputs on or off shall be treated as a Safety issue. (See safety SOP)

7.      Inputs and outputs shall not be forced on or off with out a clear understanding of complete effect on PLC program and a second opinion.

a.      If forces are installed, they shall be removed with in 24 hours and a more permanent solution found.

b.      All forces should be documented in software and a written log before being enabled.

8.      Online programming is somewhat of a safety risk, normal procedure is to change offline and download to the PLC.

Hope this helps, if you have a specific question you can find me in our PLC discussion area at the PLC Discussion Forum.

Don Fitchett (President)

Business Industrial Network

PLC Training – The best for less

www.bin95.com

February 21, 2010 Posted by | Electrical, engineering, manufacturing, PLC | , , , , , , , , | 1 Comment

   

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