Inquiring about examples of failures that have occurred? Is your maintenance schedule based on time or condition? Have you sought advice from a manufacturer representative? Our main concerns revolve around product defects, edge wave of the strip, and dents. Currently, all maintenance schedules are time-based, but we are aiming to transition towards condition-based schedules. We are seeking guidance from a manufacturer regarding suitable materials for various plant applications. Regards, David Mumford.
quote: Originally shared by Josh: For individuals who are unfamiliar with the equipment, I have a few inquiries: Are these rolls equipped with bearings on both ends? Do motors drive these rolls? Have there been any reports of vibration or other issues with these rolls? How old are they, and do they have a designated lifespan before their surfaces wear out or become uneven? It's understandable, Josh, if you're not familiar with the equipment. Here are some key points to note: 1 - All rolls are supported by bearings, with some having seal for life bearings and others having bearing housings that are regularly greased. 2 - Around 15% of the 500 rolls are powered by DC motors through a reduction gearbox. Bridle rolls work in pairs, providing drive to the strip through a neoprene, urethane, or rubber surface with a 270-degree circumference. This setup allows the strip to move at speeds of up to 300 meters per minute. Other rolls serve to prevent the strip from coming into contact with structures and potentially causing scratches. 3 - There have been no significant reports of failures related to vibration issues. 4 - Due to previous work practices, none of the rolls were uniquely identified, making it difficult to track replacements or ages accurately. However, some rolls could be over 8 years old. To address this, we now send each roll out for repair with a unique identifying number engraved on it. Josh, I will address your remaining questions shortly. Best regards, David Mumford
David Mumford responding to Josh's previous inquiries regarding the reliability of rolling systems. It is important to consider the overall integrity of both the rolls and their driving mechanisms as complete systems. Maintenance practices have traditionally focused on motors and gearboxes, with the rolls being overlooked. However, there is now a concerted effort to prioritize their maintenance.
Products are carefully inspected for defects such as scratches, edge wear, edge wave, buckle/ripple, or dents before being shipped to customers. Changes in hardness, surface finish, or roll profile can occur over time due to various factors such as product slippage, sharp edges, inadequate roll hardness, different cleaning chemicals, or metal pickoff embedding into the roll surface. Tension in the production line can also lead to potential issues.
I hope this provides further insight into the concerns you raised, Josh. Thank you.
Upon researching the process of forming roll making, I came across valuable insights regarding the production of various cross-section profiles. Each profile necessitates a meticulously crafted set of roll tools, starting with a flower pattern that dictates the sequence of profile cross-sections for each roll stand. The roll contours are then formulated based on these flower pattern profiles. Due to the significant cost of roll sets, computer simulations are often utilized to refine and perfect the roll designs, optimizing the forming process to reduce the number of stands and material stresses in the final product. Maintaining the roll contours derived from the flower pattern profiles is crucial to ensure the quality of the final product. Is this a concern for your rolls as well? The potential changes to surface profiles due to prolonged use of the rolls is a key consideration that should not be overlooked.
The original equipment manufacturer (OEM) responsible for the production of the rolls will have a good understanding of what specific areas to inspect. This knowledge is crucial in ensuring product quality and performance.
Maintaining and keeping records of 500 rolls in a mill requires proper inspection and maintenance procedures. Utilizing a Computerized Maintenance Management System (CMMS) can streamline this process and ensure equipment efficiency. Has your mill implemented CMMS for record-keeping and maintenance tracking purposes?
Can roll materials such as hard chrome, neoprene, urethane, and rubber be replaced as needed during shutdowns? These materials are commonly wrapped around roll drums, varying in material to suit different industrial needs.
Check out the quote provided by Josh regarding the roll making process. At our facility, we receive 28-ton coiled products like zinclume or galvanized material which is then unrolled and processed through our system. After painting, the material is recoiled into smaller coils (ranging from 2 to 10 tons) before being sent out to other companies for further roll forming, such as for corrugated roofing or guttering. Despite our plant's age, we lack OEM specifications for some equipment. We utilize SAP as our CMMS system to store basic measurements. The drawings for our rolls include details like surface material thickness, roughness, and hardness. In cases of wear, we may send the rolls off to have the material removed and recovered. For history tracking, I classify these details as roll profiling. How would you suggest storing this information? - David, Condition Monitoring Specialist. Find more details in the attached Tower Roll Profile document.
- 19-01-2025
- Jessica Freeman
Looking for ways to track and monitor inspection results effectively in the oil and gas industry? Storing them in a filing system or digital directory on your computer is a common practice. There are specialized software solutions available that can help you monitor thickness wear and pressure vessel wall reduction in pipelines. These software programs can provide alerts and reminders for minimum wall thickness requirements. If this is what you're searching for, these tools could be just what you need to keep your inspection results organized and easily accessible.
There is an Inspection Management feature within SAP Logistics that is frequently underutilized by users. It is uncertain whether this module can serve your specific needs.
Would you mind if I revisit your initial post and provide my comments below? Our goal is to enhance the reliability of our rolls. You mentioned an issue with unreliability - could you elaborate on this? It seems that the problem arises when chunks of the roll material are removed, leading to a shutdown of the production line for replacement. How frequently does this occur? What causes these chunks to be removed - is it due to reaching a minimum diameter or other factors like stress concentration? Have you considered conducting a root cause analysis to address this issue effectively? Where exactly are these chunks removed from - the deepest wear region or any part of the rolls? Do companies have specific maintenance procedures for roll management?
Some companies may have maintenance protocols, but they may not be specifically tailored for rolls unless they are in the same industry. In terms of checks, do you assess hardness, surface finish, roll profile, or do you replace them based on a predetermined date range or when defects arise? Consider evaluating operational parameters as well. Scheduled replacements may be more beneficial than waiting for defects to arise to reduce production downtime.
How are measurements stored - do you use manual filing, computer systems, or dedicated inspection software? What is the frequency of inspections? Is the wear of the roll predictable based on usage, or is it more irregular as shown in the attached sample? How long does it typically take before reaching the minimum diameter or experiencing chunking? Do you establish limits for the roll material's lifespan or have a designated wear life for the materials used? How long is the expected lifespan of each roll material before replacement is required?
In certain instances, we have observed abnormal wear on the neoprene material, as illustrated in the attached PDF. The black line represents the wear pattern when a straight edge is placed across the roll and feeler gauges are used to measure the gap. 940mm and 1310mm are the two standard widths of painted products. This phenomenon is what I refer to as roll profiling. I am curious as to why the wear profile on the roll is uneven. Could this indicate that the load is not evenly distributed on the roll? Will the uneven wear pattern be replicated once the roll material is replaced with a new one?
1 - We have a spreadsheet in xls format specifically for recording the circumference of rolls to identify any potential causes of dent defects in the final product. This is currently the only storage system in place for this data. 2 - Our measurement point system within SAP is utilized for storing data related to DC motor maintenance, oil analysis, and equipment runtime. This system could also be considered for storing information on roll wear. 3 - Chunking, a random failure in our operations, can be attributed to various factors that we are actively addressing by improving our operational parameters. Uneven roll wear may be due to tensions within the product, which undergoes processes like hot rolling, cold rolling, and coating before reaching the painting stage. These processes can result in slight length variations across the product, leading to inconsistent tensions that cause uneven wear on the rolls. Burr edges on the product can also contribute to uneven wear. 4 - To investigate a recent failure, a tower profile report was generated for the first time. The affected roll was sent for grinding to restore parallelism. This particular roll features a neoprene layer on a steel barrel, allowing for the neoprene to be ground down and the roll to be reused until it reaches a minimum thickness. Maintenance is scheduled for a 48-hour window every 13 weeks, highlighting the need for improved inspections, replacements, and planning during these maintenance periods.
Maintenance is crucial for ensuring smooth operations in manufacturing plants. Our maintenance window occurs every 13 weeks, lasting 48 hours. This is an opportune time to enhance our inspection, replacement, and planning processes. It is essential to have a fallback or insurance plan in place during this period.
How many rolls typically experience issues during this maintenance window? What is the expected downtime for replacing materials in each roll? Do you conduct inspections on all 500 rolls every 13 weeks, or do you stagger them? Are all 500 rolls part of a single production line, or are they spread across parallel production lines? These aspects play a vital role in optimizing plant efficiency.
- 19-01-2025
- Shawn Thompson
To ensure smooth and reliable production in the long term, it is crucial to analyze and address issues such as chunking and uneven profiling. This process, known as operational process parameter quality control in Japanese terminology, is essential for minimizing or eliminating problems. In the Toyota production line, is there any allowance for shutdowns or is it a 24/7 continuous production system? Some may refer to this process as defect elimination, which aims to rectify issues like varying lengths and slight burrs on products.
In order to identify rolls that may cause defects in the finished product, we currently rely on an XLS spreadsheet for measuring roll circumference. However, there is no other centralized system for storing this information. Alternatively, we use SAP's measurement point system for storing data related to DC Motor Maint, Oil Analysis, and Equipment Runtime. One potential solution could be utilizing the CMMS to record all maintenance and inspection activities for rolls and other equipment, with links to roll inspection results stored in a computer directory. Consider collecting sufficient data over the long term to conduct reliability analyses.
quote: In a typical 13-week period, how many rolls experience issues to meet the tight 48-hour shutdown window? How much time is needed to replace each roll with new material? Are all 500 rolls inspected every 13 weeks or is there a staggered approach? Are the 500 rolls part of one continuous production line or multiple parallel lines? The 13-week inspection cycle is crucial for maintaining reliable 24/7 production and preventing breakdowns. Approximately 6 rolls are replaced every 13 weeks, with a turnaround time of around 4 weeks per roll. A line run inspection covers 99.9% of all rolls, with visual inspections conducted on about 70% annually and profiling done on only 3 rolls. There are two separate production lines in operation. Regards, David Mumford.
4. Are both production lines running simultaneously? The total planned downtime for the two lines is calculated as 2 days x 2 lines x 54/13 = 16.6 days. Are there any unplanned downtimes due to issues like chunking, uneven profiling, or stoppages outside the 48-hour shutdown period? Is the rolling mill solely focused on the Australian market, and how does demand compare to production? Can production easily meet the current demand levels?
Quote by Josh discussing the operation of two separate production lines running simultaneously. The total planned downtime is calculated as 16.6 days. Are there any unplanned downtimes due to issues like chunking, uneven profiling, or other stoppages beyond the specified 48-hour shutdown period? Does the rolling mill exclusively serve the Australian market? How does demand compare to production, and is production able to meet demand efficiently? The production runs 24/7, with an annual 5 to 7-day shutdown for maintenance or upgrades. While occasional roll failures occur between maintenance periods, they are rare. 95% of production is for the Australian market, with some decline in exports post-GFC. Production is based on customer demand, and currently, the mill is operating at full capacity. Regards, David.
Each mill requires an average of 10 days of shutdown annually, totaling 20.6 days for two mills. This schedule is deemed acceptable.
What is the typical time required for the mill to cool down and restart? Are there any delays in the process?
Josh asked how long it takes to cool down and start up the mill again. He inquired about any potential slowdown times during this process. The cooling down, isolations, tool time, de-isolations, and warm up/line run conditions are all factors included in the 48-hour downtime period. This downtime is measured from the last prime painted coil to the first prime painted coil. Maintaining this 48-hour downtime is crucial for meeting maintenance KPIs and ensuring that maintenance is completed on time and within budget. Regards, David.
At our facility, unexpected downtime caused by roll failures during maintenance is infrequent. Therefore, our unplanned downtimes are kept to a minimum. Can you provide information on the time needed to replace a roll with its spare?
Have you decided on a storage solution for your rolls yet? Are you able to make any updates to the online discussion forum?
- 19-01-2025
- Quentin Foster
Can analyzing reliability growth plots of past failures enhance the reliability of rolls, similar to the examples provided in this informative article on maintenanceforums.com?
Currently, we are in the process of evaluating the 61 Maintenance Plans (MP) linked to the 500 rolls in our inventory. The majority of these MP's are saved in a DOS based txt format, and any updates must be converted into a word-based format. During Line Run MP's, technicians also inspect other components near the rolls such as guards, motors, pumps, fans, and oil levels. During Line stop inspections, the focus will be on the critical rolls known to potentially cause problems. These inspections will involve an Inspection Test Plan (ITP) covering hardness, circumference, and roll profile, with specified limits that require approval from the designated Person In Charge. Cheers, David.