MNF1_HW001 Homework 1

	סטודנט א’	סטודנט ב’
שם	עידו פנג בנטוב	ניר קרל
ת”ז	322869140	322437203
דואר אלקטרוני	ido.fang@campus.technion.ac.il	nir.karl@campus.technion.ac.il

Question 1

You need to produce a pedal for aircraft steering. Choose two processes that can fit - one from the casting process group and the other from the bulk deformation processing group.

Part a

Select the processes and justify your choice (list technological advantages of the chosen processes: each one from its group).

Solution:
Here are a couple of suitable processes (one casting process, and one bulk deformation process):

1. Low pressure permanent mold casting: the dimensional accuracy offered by this process is superior, making it suitable for the pedal component, that has to meet exact specifications; it is also suitable for producing a large quantity of components.
2. Forging: In forging, the grain structure is strong; it also has good resistance to fatigue relevant for parts subjected to repeated stresses like a steering pedal on an airplane.

Part b

Make a qualitative comparison between the selected processes.

Solution:

	Low Pressure Permanent Mold Casting	Forging
Strength	Good, but generally lower than forged parts	Excellent, due to grain alignment and deformation
Surface Finish	Better than sand casting, may still require some finishing	Usually requires machining, but can achieve good finishes
Complexity of Shapes	Best for relatively simple to moderately complex shapes	Best for simple to moderately complex shapes
Production Volume	Suitable for medium to high volume production	Applied to low and high volume, but high setup cost for low volume
Cost	High initial setup cost, but lower cost per part in large volumes	High initial setup cost, and higher cost per part in large volumes

Part c

Select the preferable process from the two processes you have chosen and compared previously, and justify your choice.

Solution:
I chose Forging for the following reason:

• Strength: Forging makes the part very strong. This thing is really very important for an aircraft steering pedal as it has to bear a lot of stress.
• Durability and Toughness: Forged parts are more durable and tough. They can handle impacts and won’t wear out quickly, which is required for a part that is used a lot.
• Fatigue Resistance: The forging process yields excellent fatigue resistance. Since the pedal will be used time after time, it needs to withstand constant use without failing.

Question 2

Consider an economical aspect of a manufacturing. Assume that the pedal (see the previous question) is made by casting. Which casting process would you choose if you had to produce:
1.      Series of 5 discs?
2.      Series of 100 disks?
3.      Series of 1000 disks?
4.      Series of 10000 disks?
5.      Series of 100,000 disks?
What are the technological disadvantages of each casting process from the processes you have chosen?

Solution:

1. Series of 5 Discs: Sand Casting
   Its technological disadvantages are :

   • Dimensional accuracy and surface finish is lower than other methods.
   • Greater porosity and defects
   • Large amount of post-processing like machining and finishing is required.

2. Series of 100 Discs: Shell Mold Casting
   Its technological disadvantages are :

   • Initial cost for the metal patterns are higher.
   • Limited to small to medium size components.

3. Series of 1,000 Discs: Investment Casting
   its technological disadvantages are:

   • High production cost due to labor-intensive process.
   • Time-consuming since a lot of steps are involved in preparation of wax pattern and building up the ceramic shell.
   • Limited only to small parts since the ceramic shell used may be fragile, which limits it to making small components only.

4. Series of 10,000 discs: Low-Pressure Casting
   Its technological disadvantages are:

   • High initial set-up cost for equipment
   • Limited to alloy types since some alloys require a lot of pressure
   • Needs precise control of pressure and temperature to ensure quality​.

5. Series of 100,000 discs: Die Casting
   its technological disadvantages:

   • High initial cost for dies and equipment: very high.
   • Restricted only to non-ferrous metals like aluminum, zinc, and magnesium.
   • Risk of air entrapment and porosity in the final product.