NDI MAG PARTICAL
Terms
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- Magnetism?
- The ability of matter to attract matter to itself.
- Magnetiization?
- The process by which elementary magnetic domains of a material are alighned predominantly in one direction.
- magnetic domains?
- Materials that can be magnetized possess atoms that group into submicroscopic regions.
- Un-magnetized domains are aligned how?
- They are randomly oriantated.
- Magnetized domains are aligned how?
- The are align themselves parallel with the magnetic field.
- poles are attacted to earths magnetic pole and are therefore called?
- North and south pole.
- Objects are magnetized when part or all of its molecules are what?
- Aligned
- This quality of having two opposite magnetic poles is called?
- Polarity
- A conceptual representation of magnet flux that can be illustrated vy the line pattern produced when iron fillings are sprinkled on paper laid over a permanent magnet?
- Mangetic lines of force.
- The strength of the magnetic field is?
- field intensity
- represents the level of magnetism or?
- flux density
- flux lines are proportional to the what?
- amount of magnetism in parts
- What seeks a new path around surface cracks due to high reluctance of air?
- magnetic flux lines
- when a magnetic field is inturupted by a discontinuity?
- leakage field
- the stronger the leakage field the what?
- The closer the discontinuity is to the surface.
- magnetic fields must be in a faborable direction with respect to a discontinuity to produce an indication. This is called what?
- effects of flux direction
- Best results for inspecting discontinuities are optained when?
- flux lines are perpendicular to it.
- when magnetic field has little or no effect on the material?
- Diamagnetic
- when magnetic field has some effects on the material?
- paramagnetic
- when magnetic field has great effect on the material?
- ferromagnetic
- what procedure do you clamp the part between the contact plates to induce circular field?
- circular magnetism1
- what is used for hollow parts?
- Central conductor bar
- Why do you do circular magnitization first?
- because you can not verify magnetization or demag
- when parts are placed in a coil you are doing what?
- longitudinal magnetization
- In lognitudinal magnetization poles run?
- South to north inside the part.
- what kinds of magnets have longitudinal fields?
- BAR
- ease of a magnet to be magnetized is know as?
- permeability
- ease of magnetization indicates?
- high permability
- difficulty of magnetization indicates?
- low permability
- Property of a metal to retain magnetic FIELD after the magnetizing force has been removed.
- retentivity
- metals with strong magnetic fields have high?
- retentivity
- Low retentivity means what?
- the part loses most of its magnetizim
- magnetism remaining after a magnetic force has been removed?
- residual magnetism
- chemical properties and size and shape of the material determine what?
- The amount of residual magnetization.
- what is reluctance?
- The resistance of a material to establishment of magnetic flux.
- negitive or revers magnetizing force used to reduce magnetic field?
- coercive force
- If magnetic force is reversed and gradually removed what will happen?
- magnetism will diminish.
- What is electrical current used for?
- is use to induce or creat magnetic fields in parts.
- what type of current as a single phase or multipule phase?
- A/C
- what type of currentis used for surface detections?
- A/C
- DC is the bes sourced of?
- Best sorce of rectified A/C
- If you are doing 100% inspection what type of current will you use?
- D/C
- When an electrical current is passed through a conductor what happens?
- a magnetic field is formed arount the conductor.
- Amount of electrical current determines the amount of what?
- amount of strength it will have
- the stength in a coil conductor is determined by?
- The amount of loops
- The H-710G Is?
- Horizontal stationary inspection unit.
- H-710G uses what type of partical application?
- Wet partical only!
- KCH-3D IS WHAT?
- a MOBILE UNIT
- What type of partical application does the KCH-3d use?
- Wet or dry
- What are the duty cylces for a KCH-3d?
-
0-600 amps continous use
600-1200 amps 3 min on-5min off
1200-2000- 1 min on 5 min off
2000-3000- 1 min on 10 min off
These are all for AC - DC output duty cycles for KCH-3D?
-
0-1250- continous
1250-2000- 1 min on 5 min off
2000-3000- 1 min on 10 min off - DA-200(parker probe) and the TTU-432/E are used and transported how?
- Used on ship or shore and are hand carried.
- The DA-200 and the TTU432E use what type of partical applicaltion?
- Wet or dry
- The DA-200 and the TU432E are powered by?
- single phase HWRAC
- The DA-200 and the TTU432E use what type of current for Demag?
-
AC withdraw for both
AC decay for the TTU432E - DA-200 is what type of device?
- Yoke type that only provided logitudinal.
- How due you apply dry particals?
- by hand with a rubber squeeze bulb or plastic squeeze bottle.
- How do you apply wet particals?
- bath or aerosol
- What is the residual method of application for particals?
- apply power, stop power, apply bath, stop bath
- apply bath, apply power, stop bath, stop power is what type of method.
- continous which is the most common.
- what is the amps for a uniform and cylindrical in shape?
- 300-800 normally 500
- low permeability alloys or inclusions amps would be?
- 800
- the greatest two distances on the outside of the part are?
- the distance.
- What formula do you use to find the wall thickness?
- (cbc)+2(wt)=D
- what formula do you use to get your head shot?
- Diameter x type steel.
- what formula do you use to determain the number of turn?
-
c
-----
4(CBC) - How do you determain your circumfrence for your CBC turns formula?
- ID X pie
- Why is it critical to determain the cross sectional area of a part compared to the cross sectional area of the coil?
- So that you know if the part goes on the bottom or centered in the coil.
- What is the formula to find the area of the coil?
- A=pie X Rsq
- for the area of a rectangle or square part you would use what formula?
- A=H X W
- If the cross sectional are of the part is less than 10% of the coil area where does your part go
- bottom of the coil.
- when your parts cross sectional area is greater then the area of the coil your part goes?
- centered in the coil
- What formula do you use to find the affective diameter of a hollow part?
- draw it!
- Length to diameter ratio as to be greater than or less than what.
- Greater than 2in or less then 15in if its over you use 15 if its under you use extension.
- magnetizing fields extend how far from the center of the part?
- 6-9 inches
- why is it critical to determine the relationship between the cross sectional area of the part and the cross sectional area of the coil?
- So that you know where to put your part inside the coil?
- to find the area of the coil and the part what formula would you use or circuar areas?
- draw it/say it.
- To find the area of a square what formula do you use?
- draw it or say it
- for the part to be on the bottom the cross sectional area of the part has to be less than what
- 10%
- What formula would you use to find the effective diameter of a circle and a square?
- draw it
- (L/D) determines what?
- The effective are of the field distance.
- Your length to diameter as to be in between a ratio of what. If its over or under what do you do?
- Between 2-15 in. Over you use 15 and under you use extensions.
- the useful magnetizing field extends how far in the coils?
- 6-9in for the center line each way
- How much over lap do you need for if your part is 60 inches and how many times would you shot it?
- Its to big you would have to do a cable wrap.
- What is the formula for a part lying in bottom of coil?
- draw it
- whatis the formula for centering a part in the coil?
- draw it
- what is the formula for cable wrap?
- draw it?
- What is the purpose of demagnetization?
- to reduce the magnetic field retained in the part.
- Aircraft ferromagnetic parts are demaged when?
-
part is installed on a/c
part needs further machining
welding is involved
ball bearings or gear teeth
effects coating
prevents proper cleaning - mangetic fields do what continously>
- reversing and decreasing at the same time
- decreased magnetism is accomplished by?
- smaller and smaller hystersis loops created by decreasing currnet.
- The smaller the hysteresis loop produced the more what?
- Demag that has been accomplished.
- what type of dmag is more comvienent but does not penetrate very deep below the surface?
- AC
- What kind of demage works well on larg parts?
- AC step down. and AC decay
- AC coil withdraw is more suitable for what?
- Small parts and larg numbers of parts.
- What type of dmag is the most complete and affective?
- DC Multi point reversing step down
- when dmaging you want to get the residual to what?
- the lowest posible level.
- a part is considered to be satisfactorily demaged when its mag field is at or be low how many gauss meter or below what for the feild indicator?
- 3 and 2
- what is the most accurate way to messure residual magnetism?
- Field indcator
- when do you have to have your part lying east to west for mesuring residual?
- when you use a compass indicator.
- What are the six things you need to learn about a part when you recive it?
- alloy, shape, size, surface condition, permability, and retentivity
- what type of partical insures a complete coverage, partical mobility, and indicates tight defects?
- WET
- Wet partical charachteristics?
-
globular/round
.0002-.006 in
color - what collor is visible particals?
- Black or red
- what is the only authorized partical type for A/C?
- Wet flourecent
- what type of partical is considered superior in detecting subsurface discontinuities but lacks mobility and are harder to apply?
- DRY
- dry partical charachteristics?
-
elongated rod shaped
.002-.006 in
gray, black, red, or yellow - what are the two different directions of magnetic fields?
- longitudinal or circular
- When using a mag bench what do you stand on?
- isulating floor matting rated for the voltage of equipment
- what is the Need for process control?
- MAG partical is not a fail safe method.
- what are two reasons flaws can be present and not indicated?
- substandard material or equipment and process diviation
- What is the primary reason for material degradation>
- contamination
- What are the 5 things that cause material degradation>
- water, organic coatings, organic solvants, dirt, soil , other insoluble materials, and acid an alkelines.
- At what temp does heat degradation cause flourecents to go bad and what temp destroys them?
- 140 and 250 degrees F
- material contamination, equipment malfuction, and procedure diviation are what?
- Directly porportional to the no of parts inspected.
- why are minimul test schedules set?
- Due to the lake of uniformity of work load.
- new material needs to be what be for put into service?
- tested
- You perform a petroleum based vehicle contamination check prior to what?
- mixing inspection bath
- petroleum based vehicles have to sit for how long before performing a check?
- 1 hour in original container
- how do you inspect for flourecents you your petroleum?
- with a black light
- How do you perform a bath contamination check?
- using a cetrifuge tube
- partical contamination about recommended levels could cause what?
- excessive background indications and below limits may miss defects.
- what do you have to test daily and after 8 hrs of continuous use.
- your bath
- when using the centifuge tube how do you messure fluorecent consentration and the visible particle concentration
-
.1-.4 for fluorecent
1.2-2.4 for visible - petroleum based contamination check is performed when?
- prior to each use at least once each day.
- examain fluid in centrifuge tube it should not do what?
- should not fluorece
- pet contamination should not exceed what?
- 30% of bath concetrate
- background fluor check should be performed when?
- Prior to each use and after every 8 hrs of countinious use.
- what tool is used to check stationary voltage?
- keto tool
- how often do you check AC/DC on a stationary unit?
- every seven days
- perform amperage inticator accuracy check when?
- Every six months
- perform quick break check every?
- 60 days
- what is a quck break check for?
-
checks rapid colaps of magnetic field
tested at 2000 amps for .5 sec. - ded weight lift check is done?
- every 30days
- dead lift check is performed on what?
- electromagnetic yokes DA-200
- interpretation
- determination of what causes and indication
- surface indications are usually?
- well defined build up of particals
- subsurface defects are indications are usually
- broad and fuzzy
- Surface discontinuites are more harmfull then?
- subsurface
- Sharp discontinuies such as fatigue cracks and grinding cracks are more harmful then
- rounded discontunities
- discontinuities weather surface or subsurface that lies at a right angle to applied stress is more likely to be harmful then?
- one that lies parallel to applied stress.
- Classify deffect indications?
-
A-positive defect
B-questionable
C-No defect
SD-surface defect - what is an extension of the magnetic particle inspection method used for detecting flaws in problem areas?
- mag rubber inspection
- What is manetic rubber inspection used for?
-
areas with limited visual accessability.
coted surfaces
complex shapes and edges - MRI procedures?
- obtain material, clean area, remove surface inperfections, form resevior dam.
- MRI mixing and measuring?
-
must be mixed good with no streaks or color variation.
messure one gram runbber bas equals on cubic centimeter base material - Perferred magnetizaion method for MRI?
-
DC portables.
May also use mobile or stationary.
stationary has limited use. - Defect to field orientation. when using portable equip?
-
Pour mixed materials
mag in one direction
wait 60 sec
rotate probe 90 degrees and remag
allow to cure. - what do use use to examine MRI indications
- 7x - 10x illuminated magnifing glass.
- Interpretation?
- Determination of what causes a indication.
- Surface indications?
- Well defined build up of particals.
- Subsurface indications?
- Usually broad and fuzzy
- Surface discontinuities are more harmful than?
- Subsurface.
- You should perform and amerage indicator accuracy check how often?
-
at least once every 6 mon.
Check for proper output - Quick break check is performed when?
-
Every 60 days.
Check for rapid collaps of magnetic field.
Check using 2000 amps for .5 sec. - Dead weight lift check is performed on what unit?
- DA-200 parker probe.
- Dead weight lift check is performed how often?
-
Every 30 days
Checks for proper AC and DC - What are the inspection procedures for Dead weight check For AC and DC?
-
For AC space legs of yoke two to four inches aprt place 10 lbs weight and lift weight with unit engaged.
For DC Use 30 lbs weight.
for 40-50 lbs test spread legs 4-6 inches apart. - magnetic partical inspection includes exposure to?
- oil, pastes, and electrical current.
- Flaws can be present and not indicated for a number of reasons name two?
- Substandard materials either new or through service degradation or process diviation in equipment procedures or condition.
- New material must what before use?
- tested
- petroleum based vehicle check done when?
- prior to mixing inspection bath.
- before performing pet base vehicle check it must sit for how long?
- 1 hour
- in use bath concentration camp?
- used to insure proper particle to bath ratio.
- Bath concentration check is done when?
-
Performed daily and after 8 hours of consecutive use
Flourecent particals should be .1-.4 and 1.2-2.4 for visible particals - pet based contamination check is performed when?
-
Prior to use at least once a day.
Contamination will not fluorece.
Contamination shall not exceed 30% - background flourecenet checkshall be performed when?
- Prior to each day and after every 8 hours of continous use.
- arosal cans should be checked for?
- performance and residual magnetism propr to each use and demaged if necessary
- Mobility checks are performed.
-
On dry powder materials at least once a day prior to use.
Or every seven days. - System effectiveness check is done?
-
At least every seven days with ketos tool stell ring inspection
It is used to verify aperage. - For system effectivness you can see how many indications on AC and DC
-
AC-1000 1 line
DC- 1400 3 holes, 2500-5 holes, and 3400-6 holes.