وجدان حسن حمودي مدرس مساعد

1. وجدان حسن حمودي مدرس مساعد

3. Concept, Importance of Maintenance, Objectives, and Function Maintenance: Means all activities that maintain facilities and equipment in good order so that a system can perform as intended. Maintenance: to keep assets in satisfactory condition In general, maintenance activities are classified into two groups: 1) Building and Grounds included: building, parking lots, lawns, fences. 2) Equipment maintenance: Maintain machinery and equipment is good working order and making all necessary repairs. Maintenance: is combination of any actions carried out to retain an Item in or restore it to acceptable condition.

4. Neglecting will lead to: 1) Frequent break down. 2) Increase down time Down time: is the period of time during which an item is not in condition perform its intended function. 3) Fast deterioration of equipment. 4) Loss of production 5) Low motivation of employees. 6) Cost of Production will rise.

5. Importance of Maintenance • Enhanced safety: will maintain facilities are less likely behaves in an unpredictable or non-standard way or fail outright, all of which could pose hazard to staff. • Increased reliability: this leads to less time lost while facilities are repaired, less disruption to the normal activities of operation, and less variation in output rates. • Higher Quality: Badly Maintained equipment is more likely to perform below standard and cause Quality errors. • Lower operating cost: Many pieces of process technology run more efficiently when regularly serviced. • Longer life span: regular care can prolong the effective life of facilities by reducing the Problem in operation whose cumulative effect causes deterioration. • Higher end value: well-maintained facilities are generally easier to dispose of into the second hand market.

6. Importance of Maintenance:(other) • The importance of plant maintenance varies with the type of plant and its production. • Equipment breaks down leads to an inevitable loss of production. • An improperly maintenance or neglected plant will sooner or later require expensive and frequents repair, because with passage of time all machines or other facilities of wear out and need to be maintain to function properly. • Plant maintenance play a preeminent role in production management ,because plant break down creates problems such as:

7. Loss in production time • Re scheduling of production. • spoilt material (because sudden stoppage of process damages in process materials) • failure to recover over heads(because of loss in production hours) • need for over time • need for suborn trating work • Temporary work shortages workers require alternative work.

8. Objectives of Maintenance: (main) the goal of maintenance is to keep the production system good working order at minimal cost. There are several reasons for waiting to keep equipment and machines in good operating condition, such as to: 1)Avoid production or service disruptions. 2) Not add to production or service cost. 3) Maintain high Quality. 4) Avoid missed delivery dates.

9. Secondary objectives for maintenance • To enable product or service Quality and customer satisfaction to achieved through correctly adjusted, serviced and operated equipment. • To maximize the useful life of the equipment • To minimize the total production or operating costs directly attributable to equipment service and repair. • To minimize the frequency and severity of interruption to operating process • To maximize production capacity from the given equipment resources • To keep equipment safe and prevent the development of safety hazard

10. Function of maintenance: The different function of the maintenance department is as following: 1) Inspection: is concerned with the routine checks of the plant facilities to examine their condition and to check for needed repairs, to ensure the safe and efficient operation of equipment and machinery  Item received from vendors are Inspected for their fitness.  Frequency of inspections depends on the intensity of the use of equipment. 2) Engineering: Involves alterations and improvements in existing equipment and building to minimize breakdowns. Maint.dept. also make engineering and Supervision of construction project that will eventually become part of the plant, engineering and consulting services to production supervision are also responsibilities of Maint.dept

11. 3) Maintenance (Including prevent maint.) 4) Repairs 5) Overhaul: checking carefully and change or repair it, if necessary. 6) Construction: in some organizations, maint. deptis provided with equipment and construction Jobs also. take up personnel and it 7) Salvage: maint. dept. May also handle disposition of scrap or surplus materials.. 8) Generation and distribution of powerand other utilities 9) Administration and supervision of labor force. 10) Providing plant protection, including fire production. 11) Housekeeping: Managing preparing, and improving of work environment, it is included five steps: • Sort • Set in order • Shine • Standardization • Sustain

12. Break downs Break downs : disability the item (facilities ) to perform function due to technical defect abuse for machines , poor training to employees ,or specifications of material are bad or non-available appropriate environmental condition.

13. Type of break downs : We can reflect the type of break down in the following diagram

14. 1-Randomly break downs included the break downs that occur in any time and difficult to predict it when it happen . are divided to :- A) Expected randomly : this type need to the time for occur it , and can detected it if the intervals of periodic checks shorter form intervals of occur , therefore, then check and inspections are better means to control on it. B) Un expected randomly : this type cannot control on it because not have specific interval to occur , and make analysis of break down after it happen to know that lead to occur it.

15. 2-Periodical break downs is the break downs that happen due to use through years of production age, and divided to : A) Expected periodical : its happen periodically and can predicate in when it happen ,therefore, can decrease occurrence this type by system of check and inspection appropriate with ages of the components the machines and equipment. B) Un expected periodical : is the break downs that happen periodically , but difficult the predicate in happen it , therefore, than better remedy for it, is remedial maintenance.

16. What are the causes that lead to occurrence break down ? The following five causes that act individually or in some combination to cause equipment problems: 1-Deterioration : Parts wear out moving parts like gears, bearings and belts wear down or break, and electrical components burnout . most kinds of operational equipment eventually deteriorate, but neglect or abuse hastens their deterioration.

17. 2-Equipment ill-suited for the purpose : the equipment is utilized for purpose ( other than those for which it was designed ) the material size, or operation of equipment cannot handle the expected load , which cause accelerated deterioration breakage and product defects. 3-Failure to maintain equipment requirement: the equipment is dirty, lubricant is not replenished, dust ,and grime foul the mechanism. 4-Failure to maintain correct operating conditions : the equipment is operated at speeds , temperatures, pressures, ….. ect. ,in excess of recommended design levels. 5-Lack of skills of operators, maintenance crew and setup people .

18. Break down programs Among the major approaches used to deal with break downs are the following: 1- Standby or back up equipment, that can be quickly pressed into service. 2- Inventories of spare parts, that can be installed as need ,thereby avoiding lead time involved ordering parts. 3- Operators who are able to perform at least minor repair son their equipment. 4- Repair people who are well-trained and readily to diagnosis and correct problems with equipments .

19. Organization structure and type of maintenance We can reflect the organizational structure for maintenance dep. In the following diagram : To work satisfactory the maintenance dept. has an organization structure figure . shows the maintenance organization of plant.

20. Organization structure Maintenance manager Engineering assistant Forman planning and scheduling Forman engineering Field forman Forman shop maintenance Facilities forman Work order system Planning and estimating Scheduling Backlog control Performance reports Building Yards Fire protection Waste disposal Stem Power Water Air Maintenance Repair Lubrication Construction Engineering Design

21. The proposal target for organization structure to maintenance dept. are:- 1-A reasonably clear division of authority with little or no overlap. 2-Vertical lines of authority and responsibility should be kept as possible in other word a level which simply transmits information up and instruction down should be eliminated . 3-Fit the organization to personalities involved this means that the organization structure should be flexible and it may be revised periodically to fit changing personnel and conditions.

22. 4-In any case there are three common organization for maintenance deprt.: •Centralization organization : according this type should be department for maintenance among the departments of productive and provide it service to all productive department . •Decentralized organization :According this one should be found unit for maintenance in each department of productive. •Mixed organization : Gathered between first and second previously.

23. The following figure present type of maintenance:

24. Where : Maintenance work undertaken to keep or restore an asset to an acceptable standard at an acceptable cost and divided to: First : planned maintenance . works of the maintenance organized and carried out according to timetable pre-specified and divided to:- 1-Preventive main: work intended . to preserve an asset to prevent failure and to detect intial faults and its divided to:- a-Running main.: work implemented with the asset remaining in use b-Shut down main. : work only impemented when the asset is out of service.

25. 2-Corrective main.: work intended to restore an asset to acceptable standerd and divided to : a-Break down main .: work implement after failure but based on advance planning . b-Shut down main : work only impemented when the asset is out of service. Second : un planned main.: are activities of the maintenance that make without pre-plannig and is what called “emergence main.” That need to necessary immediately inter face to prevent occure greatest break down.

26. Trade – off between preventive and remedial maintenance Part one : preventive main.(P.M.): consists of maintenance activities performed before equipment breakdowns with the intent of keeping it operating acceptable and reducing the likelihood of break down .

27. the commone activities are : 1-Design , selection , installation of equipment and system so as to achieve acceptable reliability. 2-Perodic inspection and record keeping to assess the condition of facilities and equipment so breakdown can be avoided . 3-Perodic repetitive servicng , repair , overhauls , even though no breakdown has occured. 4-Adequate lubricant , painting , cleaning , and adjusting to maintain operation condition

28. We can divided the (PM) into tow branches: 1-Time – based (periodic ) maintenance : Consist of periodically inspecting , servicing ,and cleaning equipment and replacing parts to prevent sudden failure and specialized maintenance activities. 2-Perodictive maintenance: Applies sensors and analysis of technical data to determine when the performance of equipment is about to degrade or when it is about to break down .

29. Advantage of P.M. 1-Reduction in downtime . 2-Less standby equipments are need 3-Less over time pay for maintenance staff. 4-Less expenditure on repairs. 5-Less storage of spare parts. 6-Greater safety of employers . 7-Increase equipment life. 8-Batter product quality.

30. Part tow : Remedial maintenance = breakdown repair =corrective maintenance: consists of efforts to restore facilities and equipments to an acceptable operating condition after a breakdown has occurred .

31. Disadvantages of breakdown main. Or remedial maintenance or corrective maintenance: 1-Breakdowns generally occur at unopportunity times. This lead to poor hurried maintenance and excessive delays in production . 2-Reduction of output. 3-Faster plant deterioration. 4-Increased chances of accidents and less safety to both workers and machines. 5-More spoilt of material . 6-Direct less of profit.

32. Part three The best approach is seeking a balance between preventive main. And breakdown main. Strike a balance between preventive cost and breakdowns cost .this concept reflected in following figure:

34. Exercises :- Huntsman is a CAP firm specialization in pay roll preparation . the firm has been successful in automating much of its work using high- speed printer for check processing and report preparation . the computerized approach .however has problem over the past 20 month , the printer have broken –down at rate indicate in the following table:

35. Each time of printer breakdown ,CPA firm estimates that it loses an average 300$ in production time and service expenses. One alternative is to purchase as service contract for (PM) .even if CAP contracts for (PM) there will still be breakdowns average one breakdown for month. The price for this service is (150 $) per month. Required should the CPA firm run until breakdown poleis or contract for pm.

36. Exercise 2:- The frequency of breakdown of a machine per month is show in the table the cost of breakdown is 1000$ and the cost of PM is 1250$ per month if PM is performed, the probability of a machine breakdown is negligible. Should the manager use PM? Or would it be cheaper to repair the machine when it breakdown?

38. Exercise 3:- Each breakdown of graphic potter table at air bus industries cost 50$ find the excepted daily breakdown cost giver following data?

39. Standards measure the maintenance performance First: Maintainability: easy and speed doing the maintenance activities MTTR= (down time for repair )/number of repairs Second: Reliability : is the probability that equipment will perform perform properly under normal operating condition .one measure for reliability (R) is the probability of successful performance. R= Number of success / number of repetitions A measure related to reliability is the (mean time between failure) MTBF=total running time / No. of failures Third : Availability (A): is proportion actually available to plan available A= MATBF/MATBF+MTTR A= actual running time/ planned running time As this formula suggest , availability is increased through combination of increasing MTBF, decreasing for repair MTTR or both.

40. Ex. 20 machines are operated 100 hr. one machine fails 60 hr and other fails in 70 hr required :what is MTBF? And R?

41. EX. During a three week period tow identical machines have the following record of downtime (in minutes) for repair. Required : 1-Which machine is better in term of maintainability ? 2-Which machine is better in term of reliability ? 3-Which machine is better in term of availability ?

42. Ex : Some one supervision an operation that habitually requires readjustment by a skilled machinist once every three week 120 hr. it takes the machinist two hours to make adjustment in addition the operation is usually idled for two hours before the machinist arrives bill thinks the operator should be taught to do the adjustment .assuming the operation is not help up for anything other than the adjustment . Required : what is the availability of the operation? What are the issues in the operator doing the adjustment?

43. Fourth: Performance efficiency : is a measure of how well a machine performs while it is runnig . Its requires answering two question : 1-What is the rate efficiency ? 2-What is the speed efficiency? Rate efficiency : suppose parts that move down a chute feeding into a machine periodically jam every time parts , jam the flow of parts into machine (which is running ) is disrupted the machine operator has to dislodge the parts to resume flow. RE= Actual production volume* actual cycle time / actual running time

44. Ex: Suppose the machine runs (535 min) a day . also suppose the average daily through put of the machine is 830 units and the actual cycle time is (0.6 min/part)

45. Speed efficiency (SE): suppose the machine is designed to produce two parts, per minute the equal to (0.5 min/par) cycle time, since in actuality the machine cycle time was 0.6 min part , then the speed efficiency (SD)= SD= design cycle time/ Actual cycle time

46. Fifth: Quality rate(Q): is an index of the produce output that is non-detective or conforms to requirement. The formula to compute it is : Q=actual production volume – defect output /actual production volume

47. Ex: suppose the machine produce an average of 30 detective units out of 830 unit / day . the quality rate is :

48. Sixth : Overall Equipment effectiveness (OEE): A measure of equipment effectiveness, that incorporate availability , performance efficiency , and quality rate. OEE= A*PE*Q Importance of OEE: Improving the OEE not only increase production throughout. Its also reduces variability in product Quality and schedules and as a result need for inventory , over time rework and other costly ways of dealing with out variability . This is why JIT and TQM manufacturing plant strive for high OEE.

49. Example General: EX1 Sonya Marx operates a machine 340 minutes a day the cycle time per part on the machine is measured to be 0.8 minute and the machine specifications indicate that it should have a cycle time 0.75 min/part. What is the Performance efficiency of machine.

50. EX 2; Soya marx operates a machine (described in EX1) is scheduled to operate 390 min a day. A bout 6 part per day from the machine are rejected as non-conform. Required : what is the machine Overall Equipment Effectiveness(OEE)?