MANF4430 Reliability And Maintenance Engineering

Answer:

Introduction

As a large soft drink bottler in Melbourne, Australia, the number of complaints that Bubbly Limited (BL) has received from customers about the quality of products is a major concern that has to be resolved as quickly as possible. Most of the complaints received fall into the following four groups: scratch marks on the can, dents on the can, incorrect taste and inconsistent volume. The product specifications are: the volume in each can should be between 372 and 377 ml; the taste of the drink should have a rating of 8.5 or above, each can should have less than three scratch marks, and each can should have less than 2 dents. Therefore the company is focusing on these issues so as to establish their root causes and identify appropriate strategies of resolving them.

Findings

Some observations, sampling and testing of the bottling process and quality of final products have already been conducted and relevant data collected for five days. From the data collected over the 5-day period, the following are some of the key findings:

• Speed has a very small effect on the number of scratch marks and dents at all the selected four check points. This is because the average number of scratch marks or dents on the can is almost the same regardless of whether the filler speed is set to very fast, fast, mild or slow.
• There was no defective can (ones with three or more scratch marks) at checkpoint A. This means that all empty tin cans supplied by Quality Can Pty ltd do not have any defects. In other words, all scratch marks were incurred during the bottling process.
• There were a total of 20 defective cans (ones with three or more scratch marks) at checkpoint B. Even though this number represents a very small percentage of the total cans that pass through this point, the scratch marks were caused by the lid sealer. Interestingly, all the defective cans at checkpoint B had only three scratch marks (there was no can with more than three scratch marks at checkpoint B).
• There were 22 and 11 defective cans (ones with two or more dents) at checkpoint C and D respectively. This means that both packer 1 and packer 2 caused the dents, with the former causing more dents, as shown in the graph provided in Figure 1 below. Interestingly, all the defective cans at checkpoint C and D had only two dents (there was no can had more than 2 dents). It also important to note that all the dents were identified at checkpoint C and D meaning that all the dents were incurred by the packers since no dent was found on the cans before the packers. 

• A total of 50 cans had volume less than 372ml (under-filled) while 68 cans had volume greater than 377ml (over-filled), as shown by the graph in Figure 2 below. The under-filling and over-filling may be caused by the imprecision of the filling machine, inappropriate timing of the filling process, the sluggishness of the fillers or the inaccuracy of the ultrasound technology used to detect the height of the drink. The fact that there was under-filing and over-filling shows that the process of filling (including the technology, machines and fillers) was not consistent. 

• A total of 39 had a taste rating below the desired 8.5 (taste of the drink was “off”). The “off” taste may be caused by several reasons including: poor quality of ingredients used (low quality carbonated water and concentrates/syrups), incorrect proportions of the ingredients, inadequate mixing of the ingredients and insufficient time for the ingredients to blend.  
• The average number of cans per minute at counter 1 and 2 was 1,518 and 1,503 respectively. This means that productivity of packer 1 was higher than packer 2.

Recommendations

From the findings above, the following are some of the recommendations that can help in resolving the problems and reduce customer complaints:

• The company should change or upgrade the machine type of lid sealer or technology used for sealing the cans so as to avoid making scratch marks on the cans. This is because all scratch marks were incurred by the lid sealer.
• The company should change or upgrade the machines or technology used by both packer 1 and 2. This will help in preventing making dents on the cans. This is because all dents were incurred by the packers.
• The company should conduct more analysis to determine the exact root cause of the under-filling and over-filling. For now, there is need to improve the efficiency and precision of the machines and devices used to measure the quantities filled in each can and the accuracy of machines used for filling the cans. The fillers should also be trained more on how to improve accuracy of filling process. It is also possible that the under-filling and over-filling may be caused by the imprecision of the method used to measure volume in the can. Therefore the company should consider improving the method used to measure the volume of the drink in the can. The ultrasound technology used to measure the volume by detecting the height of the drink in the can may not be reliable as some cans may have a slightly bigger or smaller width/circumference.
• The company should examine the quality of ingredients used for making the drink (concentrates/syrups and carbonated water) to confirm that t meets the required quality standards. There is also need to check or improve the technology or machines used to measure the proportions of ingredients used for making the drink. Additionally, the company should improve the technology or machines used for mixing the ingredients. Last but not least, the company should conduct a scrutiny of the entire bottling process to ensure that there are no any foreign substances that get added to the ingredients or soda, such as rust or heavy metals from machines and equipment used.  

The company should implement the recommended actions above immediately to resolve the problems identified and prevent them from affecting both sales and the good reputation of the company.