Calculation of Compulsory Approach and Drilling Time

Q. The time taken to drill a hole through a $25mm$ thick plate with the drill rotating at $300rpm$ and moving at a feed rate of $0.25mm/rev$ is

1. $10sec$
2. $20sec$
3. $60sec$
4. $100sec$

Q. Linked Data:
Blind hole $10mm$ diameter, $50mm$ deep are being drilled in steel block, drilling spindle speed is $600rpm$, feed $0.2mm/rev,$ point angle of drill is $120$

Machining time (in $min$) per hole will be

1. $0.08$
2. $0.31$
3. $0.44$
4. $0.86$

Q. A 31.8 MM HSS drill is used to drill a hole in cast iron block 100 mm thick at cutting speed of 20 m/min and feed 0.3 mm/rev. If the over travel of drill is 4 mm and approach 9 mm, the time required to drill the hole is

1. 1 min 40 s
2. 1 min 44 s
3. 1 min 49 s
4. 1 min 53 s

Q. A hole of $20mm$ diameter is to be drilled in a steel block of $40mm$ thickness. The drilling is performed at rotational speed of $400rpm$ and feed rate of $0.1mm/rev$. The required approach and over run of the drill together is equal to the radius of the drill. The drilling time (in minute) is

1. $1.00$
2. $1.25$
3. $1.50$
4. $1.75$

Q. Find the speed range ratio for the drilling machine spindle if the minimum and maximum diameters of drills used are $5mm$ and $25mm$ respectively and if the machinability indices for the work materials are $120$ (brass) and $40$ (alloy steel)

1. $3/5$
2. $5/3$
3. $5$
4. $15$

Q. In a single pass drilling operation, a through hole of $15$ mm diameter is to be drilled in a steel plate of $50$ mm thickness. Drill spindle speed is $500$ rpm, feed is $0.2$ mm/rev and drill point angle is ${118}^o$. Assuming $2$ mm clearance at approach and exit, the total drill time (in seconds) is

1. $35.1$
2. $32.4$
3. $31.2$
4. $30.1$

Q. Through holes of $10mm$ thickness. Drill spindle speed is $300rpm$, feed $0.2mm/rev$ and drill point angle is ${120}^o$. Assuming drill overtravel of $2mm$ the time for producing a hole will be

1. $4$ seconds
2. $25$ seconds
3. $100$ seconds
4. $110$ seconds

Q. A $\varphi -20mm$ through hole is to be drilled in a $30mm$ thick plate using a double fluted, ${120}^o$ lip angle drill. The drill tip is at a distance of $3mm$ from the plate surface when cutting is started and an overtravel of $2mm$ is recommended as a margin to ensure drilling through the full thickness of the plate. If the drill rotates at $500rev/mn$ and the feed per tooth is $0.01mm$, the machining time of the operation (in $min$) will be

1. $4.5$
2. $7.5$
3. $9$
4. $10.5$

Q. A drilling machine has to be designed with $8$ spindle speeds ranging approximately between $120$ to $100rpm$. The $5th$ spindle speed is

1. $445$
2. $480$
3. $620$
4. $865$

Q.

Linked Data:
Blind hole $10mm$ diameter, $50mm$ deep are being drilled in steel block, drilling spindle speed is $600rpm$, feed $0.2mm/rev,$ point angle of drill is $120$

During the above operation, the drill wears out after producing $200$ holes.Taylor's tool life equation is of the form $V{T}^{0.3}=C,$ where $V=$ cutting speed in $m/min$ and $T=$ tool life in min. Taylor's constnat $C$ will be

1. $15$
2. $72$
3. $93$
4. $490$