Outboard Stand Maintenance Quiz

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.