Podcast
Questions and Answers
What is the first action to take if the bottom of the outboard stand is suspected to be the issue?
What is the first action to take if the bottom of the outboard stand is suspected to be the issue?
Which area should be wiped during the inspection of the outboard stand for foreign objects?
Which area should be wiped during the inspection of the outboard stand for foreign objects?
What should be done if there are burrs on the mill bed in the outboard base area?
What should be done if there are burrs on the mill bed in the outboard base area?
What is recommended if pitting or rust is found on the outboard stand?
What is recommended if pitting or rust is found on the outboard stand?
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What should be done after using a grinder on the outboard stand?
What should be done after using a grinder on the outboard stand?
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What is the main purpose of the mill face alignment chart?
What is the main purpose of the mill face alignment chart?
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Which statement correctly defines a pass in the context of rolling mills?
Which statement correctly defines a pass in the context of rolling mills?
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What is a key component of maintaining proper outboard and mill bed conditions?
What is a key component of maintaining proper outboard and mill bed conditions?
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What does the term 'reproducibility' refer to in the context of mill operations?
What does the term 'reproducibility' refer to in the context of mill operations?
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Which defines the 'keyways' in a mill context?
Which defines the 'keyways' in a mill context?
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What is a primary purpose of executing a raft alignment in rolling mills?
What is a primary purpose of executing a raft alignment in rolling mills?
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What impact does proper polishing of a coupon have in cut and etch preparation?
What impact does proper polishing of a coupon have in cut and etch preparation?
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What is the main effect of smearing during the cut and etch process?
What is the main effect of smearing during the cut and etch process?
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What is the primary purpose of zeroing out the digital indicator against the zero set block?
What is the primary purpose of zeroing out the digital indicator against the zero set block?
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When measuring the deviation of the mill face spacer, what does a positive deviation indicate?
When measuring the deviation of the mill face spacer, what does a positive deviation indicate?
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What is the significance of a nominal dimension of .500" for mill face spacer thickness?
What is the significance of a nominal dimension of .500" for mill face spacer thickness?
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What is the first step when installing the locking collar onto the shaft?
What is the first step when installing the locking collar onto the shaft?
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Why should the top and bottom shaft spacers be ground before installing the rolls?
Why should the top and bottom shaft spacers be ground before installing the rolls?
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What is an essential step to take before installing the locking collar?
What is an essential step to take before installing the locking collar?
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What should be done if a large deviation from nominal (tk=.030" from nominal") is measured?
What should be done if a large deviation from nominal (tk=.030" from nominal") is measured?
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During the adjustment of top and bottom rolls, what is the key measurement to obtain?
During the adjustment of top and bottom rolls, what is the key measurement to obtain?
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Which of the following is NOT a common issue in reproducibility?
Which of the following is NOT a common issue in reproducibility?
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What should be done if a setting cannot be made to work during the reproducibility process?
What should be done if a setting cannot be made to work during the reproducibility process?
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What is the purpose of the cut and etch testing method?
What is the purpose of the cut and etch testing method?
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Which of the following must be included in the results page during reproducibility?
Which of the following must be included in the results page during reproducibility?
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Which material characteristic can the cut and etch method reveal?
Which material characteristic can the cut and etch method reveal?
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What does a non die change sheet require during the reproducibility process?
What does a non die change sheet require during the reproducibility process?
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Which process is critical for keeping scrap rates low and improving overall equipment efficiency?
Which process is critical for keeping scrap rates low and improving overall equipment efficiency?
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What is the role of etching in the cut and etch testing method?
What is the role of etching in the cut and etch testing method?
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What is a potential consequence of poor sample preparation?
What is a potential consequence of poor sample preparation?
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Which of the following describes a crack in the material?
Which of the following describes a crack in the material?
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What can cause smearing during sample preparation?
What can cause smearing during sample preparation?
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Where are stress risers typically located?
Where are stress risers typically located?
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What is NOT considered a crack in materials?
What is NOT considered a crack in materials?
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Which step comes first in troubleshooting a welding issue?
Which step comes first in troubleshooting a welding issue?
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What does the nugget grain structure on a polished surface resemble?
What does the nugget grain structure on a polished surface resemble?
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What should NOT be part of the documentation process after troubleshooting?
What should NOT be part of the documentation process after troubleshooting?
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What is the primary purpose of analyzing a drawing with GD&T annotations when troubleshooting?
What is the primary purpose of analyzing a drawing with GD&T annotations when troubleshooting?
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Which measuring tool is NOT mentioned as appropriate for GD&T inspections?
Which measuring tool is NOT mentioned as appropriate for GD&T inspections?
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What should be done after identifying a problem area in the assembly?
What should be done after identifying a problem area in the assembly?
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Which factor can contribute to GD&T related problems during assembly?
Which factor can contribute to GD&T related problems during assembly?
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If a part has a twist upon inspection, what feature might be causing the issue?
If a part has a twist upon inspection, what feature might be causing the issue?
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When verifying tolerances using measuring tools, what should be compared?
When verifying tolerances using measuring tools, what should be compared?
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Which element is NOT a component of GD&T specified in the annotations?
Which element is NOT a component of GD&T specified in the annotations?
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What is the first step you should take when troubleshooting an assembly issue?
What is the first step you should take when troubleshooting an assembly issue?
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Study Notes
Tech 3 Skills
- Rolling mills are precision equipment; aligning stations is critical for tooling alignment
- Several different types of rolling mills exist, each with different alignment techniques
Objectives
- Upon successful course completion, students will be able to: access the mill face database, differentiate between passes and stations, define components and purpose of mill face spacers, explain different methods to keep rolling mills aligned, explain purpose of mill face alignment chart, understand proper outboard and mill bed conditions, define components of a shaft and identify a shaft in good working condition, describe how to repair a mill bed, describe purpose of inboard and outboard keyways, define purpose of alignment of rolling mills and the steps to a raft alignment and needed tools, execute a raft alignment, define reproducibility, independent verification and data availability, explain importance of reproducibility, identify common reproducibility issues, explain your role in reproducibility as a tech 3, describe cut and etch and its uses at shape, explain common cut and etch preparation failures, explain the roll of properly polishing a coupon for examination, define smearing in cut and etch, describe a proper sample for cut and etch, explain a crack on a sample, establish proper troubleshooting methodology, communicate importance of single adjustments at a time, analyze a drawing for troubleshooting,
Mill Alignment
- A rolling mill is precision equipment. Keeping the stations aligned is critical to keeping tooling aligned
- Different rolling mills at shape require different techniques to keep stations aligned
Mill Face Alignment
- Three-pass alignment is similar to mill face alignment, but focuses on one inboard stand
- Raft alignment aligns individual stations on rafts of rolling mills
- Mill face alignment aligns the entire rolling mill
- Pass: each ordered pair of tooling
- Station: one stand on the rolling mill that can accommodate a pass
Mill Face Spacer
- Custom thickness spacer (machine face spacer) keeps shaft shoulders in a straight line
- Remains with rolling mill during tooling changes
- Typically has a flat cut with station number and shaft engraved
- Through hardened
Shaft Shoulder
- Larger diameter of the shaft found on the inboard stand
- Surface against which the mill face spacer rests
Examples of Shaft Conditions
- Chipped edges around keyway might require shaft or inboard stand replacement or using a longer key
- Gouges from cutting torch typically don't require replacement if tooling slides smoothly on the shaft
Shaft Threads
- If shaft threads are not in good condition, a die set, wire brush, and files are used for repair
Items to Verify
- Check outboard stands for minimal sliding resistance
- Inspect outboard stand bottom for damage (pitting, rust, burrs)
- Ensure shafts are aligned with bearing sleeves
Outboard Stands
- Safely lift the outboard stand; clean the bottom
- Check for foreign objects (shavings, slugs) in the keyway
- Look for pitting, rust or anything that interferes with sliding on the mill bed
- Correct issues with a honing stone
- If smooth bottom, look for other issues
Mill Bed
- Clean the mill bed with rags or squeeze.
- Remove burrs with honing stone
- Grind if necessary, but wipe the area after grinding
- Ensure outboard stand slides freely
Alignment of Inboard Stand
- Two keys (inboard and outboard) on the mill bed are used for alignment
- Inboard key aligns inboard stands in the same plane
- Outboard key aligns outboard stands perpendicular to the inboard key
Alignment of Inboard Stand
- Keyways are designed with a tolerance; allows inboard stands to be slightly out of line with outboard stands
Checklist Before We Begin
- Remove all roll tooling from the station being aligned
- Ensure mill bed is clean
- Place outboard stands off the mill bed or in a safe location
Mill Face Database
- Check the mill face database in the plex before starting alignment
- If the mill is in the system, print the sheet for comparison
- Print a blank for record if no record exists and fill it in after alignment
- Turn in revised/created chart to the RFE in your area
Raft Face Alignment
- Conventional mills and rafted mills require alignment
- Use the raft face alignment kit for alignment
- Place raft cassette on sawhorses
- Unbolt and remove outboard stands
- Remove outboard stands from raft plates (if 1" adjustable stand, fork pocket screws to elevating screw)
- Ensure inboard stand bottom shafts are tight, no up/down movement
- Install bottom shaft alignment tool
- Install locking collar onto shaft and slide against mill face spacer
- Make sure mill face spacer is thoroughly cleaned before installation
- Use digital indicator to zero the tool, insert into lower port hole for measuring deviation between top and bottom spacers
Raft Face Alignment (continued)
- Determine if mill face spacer needs to be ground or replaced.
- Large deviations from nominal (.470" to .530") may indicate problems in inboard assembly
- New millface spacers should always be ground to ensure flatness
- Using top and bottom rolls from standard design (STDAT1497/1509) measure top/bottom offset of shaft alignment
- Top roll onto roll shafts; top roll first
- Ensure that top and bottom shaft spacers are ground prior to installation
- Set parallel top/bottom shafts by measuring and adjusting the vertical aluminum outboard screw
- Install top/bottom alignment rolls, slide against top and bottom alignment spacers
- Rotate top and bottom rolls
- Zerro out indicator on tool, using it to zero-set on port.
- Measure top/bottom alignment spacer deviation
- Insert zeroed indicator into lower port for measuring thickness
Reproducibility
- Reproducibility is the ability to reproduce results using the same materials and methods, essential for consistency in manufacturing
- Important in a manufacturing environment for unfamiliar operators to set up a machine based on system information
- Independent verification and data availability are crucial to proper reproducibility
Principles of Reproducibility
- Independent verification: ability for others to repeat and get similar results
- Data Availability: Data needs to be detailed, complete, accessible, and up to date
Importance of Reproducibility
- Feeding wrong steel, wrong adjustments, causing incorrect assumptions about the adjustment
- Missed steps leading to problems downstream (eg last pass)
- Equipment damage from incorrect position or shut height settings
- Difficult and time-consuming adjustments
Common Issues in Reproducibility
- Missing Date/Time
- Hand-written notes instead of computer-inputted notes
- Missing results
- Parts per adjustment (inconsistency)
- Incomplete/detailed adjustment notes
- Missing tech 3 or RFE sign-off
- Adjustments made before verification
- No tech 3 involved
Reproducibility - Trouble Shooting
- Critical skill for Tech 3s to evaluate and trouble shoot the process of reproducibility
- Verifying adjustments critical to preventing scrap (low scrap rates) and ensure overall equipment efficiency.
Cut & Etch
- Destructive testing method for evaluating weld characteristics
- Involves cutting, polishing, and etching a sample to reveal weld profile and microstructure
- Shows penetration, porosity, cold lap, lack of fusion between layers
Cut & Etch process
- Cutting: Sample cut from weld coupon
- Polishing: Cut face of sample polished for viewing
- Etching: Acid-based solution used to reveal detail
Wet Saw
- Place sample in saw vice to ensure proper sectioning
- Clamp tightly; cut at a smooth, even speed to avoid sharp flashes or burns
- Uneven cutting can create issues at the polishing station
Inspect Sample
- Check for flatness, hooks, and heavy flashing
- Belt sand to remove burn marks/beveling/hooks/flashing; prepare sample for placement on the mat
Polishing
- Replace polishing pads when rips/tears/holes exist
- Remove the mounting ring and inspect it
- Replace polishing pads, ensure the mounting ring is put back on properly. Ensure plastic backing is not peeled off (400 grit on left and 600 on the right on a monoleg)
- Press the sample on the course grit pad (left) to flatten
- Press on the fine grit pad (right) to remove coarse polish marks
Cut & Etch Samples
- Brush the starting weld with acid continuously to reveal grain structure (roots, toes)
- Ensures no debris, deep scratches, or flashing
- Monoleg return leg must be visible
- Samples must be fully etched to determine cracks
Cut & Etch Sample Preparation
- Poor Preparation: visible scratches or polishing marks, nugget grain structure is not visible
- Proper Preparation: sample displays minimal scratches, weld nugget grain structure is clear
Nugget Grain Structure
- Pattern on the polished surface of the weld nugget resembles marbling, gravel, or salt grains
Stress Risers
- Areas in the material subject to increased tension or reduced thickness, prone to cracking
- Example: undercuts and corners
Cracks
- Breaks in the material, not allowed in weld
- Typically found in top corners near stress risers
- Generally run perpendicular to the material edge
- May extend through HAZ and parent material
- Look for jagged and/or branching shape
Troubleshooting
- While troubleshooting structures may vary depending on the system, basic principles remain consistent;
- Problem identification
- Theory of Cause
- Plan of Action
- Implement the Plan
- Verify Full Functionality
- Document Findings, Actions, and Outcomes
Problem Identification
- Identify the initial problem and its likely root cause
- Note when the problem began
- See if any equipment crashes or changes precede the problem
Problem Identification (continued)
- Determine if any changes like coil changes have occurred
- Check if parts are loaded into the gauge correctly
Problem Identification (continued)
- Verify that corrections on the machine were done properly, if you are not the primary operator
Probable Cause
- Document possible causes from highest to lowest probabilities
- Evaluate part geometry
- Determine if the surfaces are flat
- Assess if the die needs shimming
Establish a Plan of Action
- Create an action plan based on the probable causes
- Determine if different personnel/tools are required
- Ensure those personnel/tools are available
Implement the Plan
- Make one change at a time when implementing the troubleshooting plan
- Test results after each change made
- Backtrack adjustments if necessary to avoid making incorrect assumptions
Verify Full Functionality
- Validate all aspects of the equipment operation
- Introduce new problems; review and fix them before making any decisions
- Account for any changes to process that might have occurred.
Document Findings
- Build a knowledge base; document your findings
- Communicate to other operators the process being used and reasons for adjustments.
GD&T Gage Applications
- Analyze the drawing thoroughly using GD&T annotations
- Identify geometric tolerances and datum references that might cause an issue
- Use measuring tools to verify if the part meets the tolerances
Interpret the Drawing
- Understand critical features and associated GD&T symbols
- Identify datum references and how they're applied
- Pay attention to tolerance values and corresponding geometric controls
Isolate the Problem Area
- Examine the failed assembly/component; determine which features don't meet required tolerances
- Analyze specific GD&T controls
- Identify inconsistent parts with the machine
Use Appropriate Measuring Tools
- Utilize CMM (coordinate measuring machines), Calipers, Dial indicators, micrometers to verify any problem with the gage
Verify Tolerances against Drawing
- Measure critical features; compare measurements against drawing tolerances
- Check for geometric deviation e.g. flatness, non-perpendicularity
Identify Root Cause
- Consider equipment wear, material variations, or improper machining techniques contributing to the problem
- Evaluate and analyze the process and any resulting problems.
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Description
Test your knowledge on the maintenance and inspection procedures for outboard stands. This quiz covers critical actions to take when issues are suspected, as well as areas to check for foreign objects. Learn best practices for maintaining the mill bed and handling rust or pitting.
