Design and Construction of Dual–Powered Heat Treatment Furnace
Chapter One
PURPOSE OF THE STUDY
This study aims to design and construct a dual-power heat treatment furnace for the Department of Mechanical Engineering Laboratory, University of Ibadan.
CHAPTER TWO
REVIEW OF RELATED LITERATURE
INTRODUCTION
This chapter presents the review of related literature on design and construction of dual-power heat treatment in the Department of Mechanical Engineering Laboratory, University of Ibadan.
PERFORMANCE EVALUATION
The performance of the diesel fired heat-treating furnace was evaluated by considering the functionality and efficiency of the furnace, ease of maintenance, safety and health considerations, and the cost effectiveness of the furnace.
FUNCTIONALITY AND EFFICIENCY OF THE FURNACE
The thermocouple tip is positioned in the furnace inner pot (1/3) one – third from the base close to the position the specimens are anchored to ensure that accurate temperature of the specimen and not that of the furnace environment is sensed. Also, the temperature controller is digital with the capability of sensing fractions of temperature thereby improving the precision and accuracy of the readings obtained from the furnace. Regular calibration of the temperature controller using an external probe is performed to ensure reliability of the temperature readings obtained from the furnace.
The furnace has a high heating rate – as fast as 61.240C/min if a temperature of 9000C is the target holding temperature. This rate of heating is far higher than that of many conventional muffle furnaces which take between 3.75 – 5.000C/min to attain 9000C. Thus within 17 minutes a temperature of 9000C can be attained resulting in time savings. Also the fuel consumption rate is less than 1.41 litres/hr. This consumption rate reduces the longer the holding time during heat treatment because the design is made to switch off the fuel supply to the burner once the temperature of the furnace exceeds the preset temperature of the furnace by 20C and then restored automatically once the temperature drops 20C from the pre-set temperature. Thus fuel savings will be achieved for longer holding times.
The furnace refractory was observed to have good heat retaining capacity, as temperatures within 9500C and below, the heat from the furnace environment is tolerable for the operator and those in the surrounding. This indicates that the refractory linings have good efficiency and effectiveness in the prevention of heat transfer from the heating chamber to the surroundings.
CHAPTER THREE
MATERIALS AND METHOD
MATERIALS
The materials utilized for the design of the diesel fired heat-treatment furnace are: 2mm thick steel sheets, kaolin clay derived from two deposits in south western Nigeria – Ijapo and Ikere Clays, silica refractory bricks, hard wood saw dust, temperature controller, thermocouple, switch, light indicators, wire, diesel, plug, burner, and chrome based alloy steel pot.
DESIGN
FURNACE CASING
The steel sheet selected is a mild steel of composition: 0.15%C, 0.45%Mn, 0.18%Si, 0.18%Si, 0.031%S, 0.001%P, 0.0005%Al, 0.0008%Ni and balance Fe. It was selected for the fabrication of the furnace casing because of its light weight, good strength, excellent formability, weldability, availability, and low cost of purchase. The furnace casing houses all the components of the furnace including: the refractory bricks and lining, the electro-technical devices (temperature controller, light indicator etc), the burner, exhaust, and heat-treating pot (chamber). The design was made taking into consideration that the control box should be attached to the casing, and the control box must have holes for easy wiring and uniform de-steaming.
CHAPTER FOUR
CONCLUSION AND RECOMMENDATIONS
INTRODUCTION
This chapter is basically on the conclusion and recommendations of the study. Heat treatment furnaces with effective temperature sensing, heat retaining capacity and controlled environment are necessary for heat-treatment operations to be successfully performed.
CONCLUSION
This research was centered on the design and construct dual-power heat treatment furnace using locally sourced materials. The design philosophy is to eliminate the use of heating elements requiring electric power which is poorly supplied in the country. On completion and testing, it was observed that the furnace has a fast heating rate (61.240C/min to attain a pre-set temperature of 9000C); and very good fuel economy – consuming less than 1.41litres/hr. It was also observed that the furnace has good heat retaining capacity; can be easily maintained and is safe for use.
RECOMMENDATIONS
Based on the findings of this study, it is recommended that:
- Fluctuating power voltage to the burner should be avoided as it can cause damage to the blower motor.
- Also, servicing of the blower/pump should be carried out at least twice a year to guarantee optimum performance of the furnace.
- The operator should always put on personal protection equipment (safety gadgets) such as hand gloves, heat protectors; and after the days work ensure that beverage rich in milk is taken to compensate for the effects of heat radiation from the furnace.
REFERENCES
- Bundgardt, K., Brandis, H. and Kroy, P. (1994). Salt Bath Carburizing and Case Hardened Steels at 9000C – 10000C., Harterei-technical publisher, 9(3): 146-153.
- Dossee, T. and Boyer, H. (1997). Practical Heat Treating. Journal of Materials Processing Technology. 14(7): 235-257.
- Fairbanks, L.H. and Palthorpe, L.G.W. (1998). Controlled Atmospheres for Heat Treatment of Metals. Revised Edition; Iron and Steel Institutes, Spain. pp. 45-60.
- George, E. Totten (2002). Steel Heat Treatment Handbook, 2nd Edition. pp 91-105.
- Netsushori, K. (1998). Various Heat Treatment Technology. Trends and prospects of heat treatment in 21st Century. 3rd Edition. pp. 201-233.
- Olanrewaju, S. O. (2000). Practical approach to metal hardening in our metallurgical industries, NMS Conference, National Metallurgical Development Center (NMOC), Jos. pp 6- 15.
- Oyawale, F. A. (2007). Design and Prototype development of a mini-Electric Arc Furnace. Pacific Journal of Science and Technology. 2007, 8(1):12 – 16.
