SOURCE:

Faculty: Engineering
Department: Industrial And Production Engineering

CONTRIBUTORS:

U-Dominic, C. M.
Godwin, H. C.

ABSTRACT:

Cable manufacturing industry is a field with a lot of variations and defects in its processes, the product quality is essential and variation in products is also a critical concern. The level of commitment to quality required to manufacture cable products in the country is enriching day by day. Making defective products in cable manufacturing, even though they can all be recovered, re-ground and the material used again, is uneconomic and non-productive because there is a large amount of money invested in the rejected product and extra energy and labor must then be spent on material recovery. Further consequences from a compromised cable product apart from the economic implications can be seen in the form of electric shocks, electrocution incidence and undisputed difficulty in delivering electrical energy to a load efficiently. In cable manufacturing, product quality is essential and variation in product is a critical issue but in most cases, results from solutions to cable defects identified during process improvement projects are not sustained so is imperative to keep extrusion systems up and running and solutions for eliminating errors and defects from cable extrusion systems are necessary. However, many solutions of integrating Knowledge Management and Six Sigma have been applied into many fields to solve similar problems of sustaining results from projects, but such integrations has not been applied in cable manufacturing industry in Nigeria or developed yet. Many organizations in the past have sought strategies to improve their extrusion process and product quality but none of the approaches were able to tackle the ever challenges of absorptive capacity (not-invented-here syndrome), development and exploration of organizational social capital, best practice replications and co-location creation. This study looked at variation and its causes, and how to improve and control a process using a synergetic support of Six Sigma-DMAIC and Knowledge Management concepts. The proposed Six Sigma-DMAIC-KM integrated solution has been validated in a cable manufacturing company in order to enhance the organizational performance. The improvements of project performance and application impacts of the proposed solution have been investigated by comparing the initial and final capability of the process of the executed projects, by comparing the initial and final Sigma level of the executed projects, by comparing initial and final economic impact assessment of the executed project. A hierarchy of decision was modeled to prioritize defect judgments on Insulation thickness failures and Insulation Surface flaws. An extrusion model was developed for predicting the appropriate cable dimension. Appropriate engineering specification was designed and tightened from (T±0.185) to (T±0.032) such that a Six sigma process could easily be captured. The completion of the study resulted to peak improvement in the capability performance, for the cable diameter using the newly-designed engineering tolerance, Cp increased from 0.22 to 1.43, Cpk increased from 0.3 to 1.23, CR decreased from 447.43% to 69.96%, ZU improved from -0.88 to 3.68, and ZL now moved from 2.22 to 4.89. DPMO reduced from 810,000 to 10, thus improving the Sigma level from the value of 0.6 to 5.2. On the Insulation thickness using the newly-derived engineering tolerance, Cp value increased from 0.45 to 0.90, Cpk increased from -0.035 to 0.09, ZU increased from -0.11 to 0.28, and ZL from 2.79 to 5.17. CR reduced from 223% to 110%, and total rejection rate was reduced from 54.64% to 38.97%. A significant reduction in DPMO from 570,000 to 420,000 was achieved, thus improving the Sigma level from 1.3 to 1.7.The economic impact assessment for the cable diameter project using quality loss function has shown that the quality loss attributed to every single 1.0s (mm) coil produced has reduced from the initial cost of ₦7.34 to ₦2.08. The percentage decrease in annual loss is estimated at about 72%, an indication that annual loss before the improvement was reduced from ₦ 1,783,620 to ₦505,440 after the process improvement. The quantity of non-conformed 1.0s (mm) cable rejected due to Insulation Surface flaws was reduced by 38.22% from the acceptable defect quantity, and about 5.6% reduction when compared with the entitlement value in the previous years. A generic knowledge-based support tool was developed in a MATLAB graphical user Interface environment that will help cable manufacturing organizations in replicating improvement studies. In general, the proposed improvement solution would serve as practical guide for adoption for cable manufacturing companies and other manufacturing companies in order to improve process performance and in becoming more knowledgeable.