Design of Biscuits Production System - Assignment Example

DESIGN OF BISCUITS PRODUCTION SYSTEM Executive summary This proposal looks at how a biscuit manufacturing company can improve production to meet the ever rising demand. The new system is expected to replace the older manual operations. From the design it was established that there can be production of a wide size range of biscuits from 50 to 80mm. Production of 85 and 90mm biscuits was not feasible since this would result to a biscuit pack of less than 8 biscuits given that the pack is to have a nominal mass of 150g.It was also established that the 1200mm conveyor cannot be used because the power requirement is beyond the 450w maximum motor requirement. Generally the cost was found to decrease as the diameter of the biscuits were increased. Table of contents 1.0 Introduction 4 1.1 Proposed Production 5 2.2. Section 2 - Conveyor belt 7 2.4. Section 4 - Heating/Cooking 9 2.5. Section 5 - Costing 10 2.6 Discussion 11 1.0 Introduction This proposal is a preliminary design for Cookies-R-Us that is a company that is experiencing high growth rate. The proposal is aimed coming up with a preliminary design and analyzing the future production of biscuits with the process encompassing a total of 5 stages namely: mixing, forming, heating, cooling and packaging as illustrated in figure 1. The system that is being used currently is manual and has the ability to produce 11 types of packets of biscuits that are sold in packs of 150g. the process of production involves the dough being cut into 70mm diameter biscuits with a thickness of 5mm. the trays used for baking are carried manually to the desired points in the kitchen for each stage of processing . The current system can be described as being labour intensive with the cost of production of a biscuits being set at $0.56 per biscuit which translates to 6.16 per pack. The system is currently at its possible maximum production rate of 50 packets per hour. 1.1 Proposed Production In order for the growing demand to be met and for the production cost to be lowered a new production line is to be put in place. The new system will have the capability of production of biscuits or different range of sizes incorporating different cooking parameters. The following are expected to be addressed upon installation of a new production line The number of biscuits produced per hour will increase There will be a reduction in the cost of production, and the production time More quality product with high consistency is expected There to be production of biscuits of various sizes and reduction of excess mass per pack of over 150g with over shoot of not more than 5% 2.1. Biscuit Size and Packet Size selection Biscuit Size Figure 2 gives the details of the biscuits layout on the conveyor with the following parameters: d – diameter of biscuit (mm) h – height or thickness of the biscuit thickness (mm)constant in all biscuit sizes m1 – mass of dough per biscuit in grams before cooking This is given by finding the volume and then multiplying by the volume Example for biscuit diameter of 50mm x5=9812.5mm3 Mass m1=density x volume =0.00085x9812.5=8.340625g The other m1 values are calculated in the same way as m2 – mass of each biscuit in grams after it has been cooked m2 =m1x0.95=8.340625 mp – is the final mass in grams of biscuits per packet = nb –number of biscuits per packet =20 po – percent overshoot (%=5%) the percentage that the finished mass of biscuits in each packet is over the target of 150 g Packet Size Each packet ca contain a nominal 150 g of biscuits, in a simple rectangular box as a single row of biscuits. There is no space between biscuits and 5 mm of space between the outer edge of the biscuits and the packet, maintained by a light plastic cradle. The cost of the packaging will be proportional to the surface area of the packet. (ie. ignores tabs, joins and the plastic cradle) The packaging is shown in Figure 3 and is defined by the parameters: a – length of packet (mm) b – width of square end of packet (mm) Ap - Surface area of packet (mm2) For d=50mm 2.2. Section 2 - Conveyor belt The conveyor belt is made of stainless steel and is available in three belt widths (see technical information section 6). The belt length is the total length of the belt incorporating area for forming, heating, cooling and the rest of the belting looping around the end rollers and under the production line. The conveyor layout is shown in Figure 4 and is defined by the parameters: D – Diameter of end roller (mm) [constant] 500mm L – Overall length of conveyor belt (full loop) [constant] =length contributed by end roller +the two hanging ends = W – width of conveyor belt (mm) [selectable see technical information] 600, 900 or 12000m A – total area of belt (m2) For w=600mm= 0.6m Area A = 0.6x2.157=12.942 M – mass of conveyor belt (kg) =Axmass/m2= 30x12.94230=388.26 m – mass of biscuit on the belt (kg) For 50mm diameter on 600mm width belt Number of biscuits on belt width wise=  Number of biscuits on belt length wise=  Number on belt =7x134=938 Therefore mass of biscuit on belt=938x8.340625g=7.823506kg as can be seen from excel sheet N – Normal force (N) due to mass of conveyor and biscuits Normal force =Total massxg=( 7.823506+388.26)x9.81=396.0835x9.81 F – Friction force (N) =396.0835x9.81=2175.75 v – Speed of conveyor (m/s) v= Pm – required mechanical power (W) Po – required output power from the motor (W) Po= Pm/efficiency= M-n - motor number [selectable see technical information] The power of the motor required = Po x Power factor=12.42X10=124.2w For this case the motor number 1 will be selected with a power output of 150 which is slightly above the required output of 124.2w 2.3. Section 3 - Production Rates t – Cooking time for each biscuit At cooking time of 20minutes the velocity of conveyor v= U_rate - Units per hour U=Number on the belt x  P_rate - packs per hour 2.4. Section 4 - Heating/Cooking T1 – initial temperature of dough [constant] T2 – final temperature of biscuit [constant] c – Specific heat of biscuit during baking [constant] E – energy to cook one biscuit Q – Heat transfer rate per biscuit Pt – thermal power required to maintain heat flow in oven during production. O-n - oven number [selectable see technical information] This shows that for 50mm biscuits the 9 kw oven will be appropriate which cost $2700 2.5. Section 5 - Costing Cb – cost per biscuit The cost per biscuit is made up of cost per biscuit for packing material cost of packing per biscuit cost of mixing per biscuit cost of dough per biscuit cost of power per biscuit Thus for 50mm biscuit Cb=0.000321+0.114286+0.028571+0.009342+0.001843 =$0.154363 Cp – cost per pack The cost per biscuit is made up of cost per pack for packing material cost of packing per pack cost of mixing per pack cost of dough per pack cost of power per pack Thus for 50mm biscuit Cp=3.5308 This is below but relatively close to the set cost of $3.7 which the cost is not to go beyond. Cc – capital cost of installing the new equipment This is compost of (for the case of 50mm biscuit case) Oven cost=$2700 Motor cost=2000 Conveyor=2588.4 Installation cost =4000 Cc=2700+2000+2588.4+4000=$11,288.4 This is well below the set target of $15000 2.6 Discussion From the results in the spread sheet it can be seen that it is not possible to produce the 85 and 90mm biscuits because this results to the number of biscuits par pack being less than 8 biscuits. It can also be observed that though using the 1200mm conveyor would give the list cost per pack the power motor power requirement when this belt is used is in the range of 600w and above. This is beyond the available motor sizes available where M-45 the biggest motor has a power of 450w. The general trend is that the increase in the diameter of the biscuits results to a lower total cost per biscuits and also a lower cost per pack of biscuits. It can also be seen that a wider conveyor results to lower of production. Read More