CNC
Computer Numeric Control
In PEB design, what does the term “Secondary Member” usually refer to?
A) Rafters
B) Purlins & Girts
C) Columns
D) Base Plates
B) Purlins & Girts
A CNC beam drilling machine with 3 spindles can drill how many sides of an H-beam simultaneously?
3 sides
In CNC drilling, the term runout (TIR) refers to
Deviation of drill rotation from true axis
Which cutting technology is most widely used for heavy steel plate cutting in PEB fabrication?
Plasma Cutting
The accuracy of CNC drilling hole positioning in structural steel fabrication is typically measured in:
A) ±0.01 mm
B) ±0.05 mm
C) ±0.1 mm
D) ±1.0 mm
C) ±0.1 mm
Which Indian standard code is most commonly followed for design of steel structures used in PEB?
A) IS 456
B) IS 2062
C) IS 800
D) IS 1893
C) IS 800
Which of the following is NOT an advantage of PEB structures?
A) Faster construction
B) Flexibility in expansion
C) Higher seismic resistance
D) Longer construction time
D) Longer construction time
In PEB fabrication, high-strength friction grip (HSFG) bolts are often preferred over normal bolts because
They resist load by friction, not shear in shank
For a 30m span PEB structure, which roof slope is most commonly adopted for efficient rainwater drainage?
A) 1°
B) 5°
C) 10°
D) 15°
B) 5°
Which of the following reduces thermal expansion errors in CNC machines during long operation?
A) Larger spindle motor
B) Automatic lubrication system
C) Linear scale feedback with thermal compensation
D) Using only carbide drills
C) Linear scale feedback with thermal compensation
In CNC drilling of steel plates for PEB connections, which coolant method is best for deep-hole drilling (>5D depth)?
Through-Spindle Coolant (TSC)
Which grade of structural steel is most commonly used in PEB fabrication in India?
A) Fe 250
B) IS 2062 E250
C) IS 2062 E350
D) Fe 415
C) IS 2062 E350
The primary load acting on a PEB industrial shed is usually?
C) Wind Load (in India, wind governs most warehouse & shed design)
The lookahead function in CNC controllers is mainly used for:
A) Estimating tool life
B) Predicting next tool change
C) Smoother motion at high feed rates
D) Preventing spindle overheating
C) Smoother motion at high feed rates
Which factor affects chatter vibrations in CNC drilling the most?
A) Cutting speed only
B) Tool geometry, rigidity & spindle RPM
C) Coolant temperature
D) Operator experience
B) Tool geometry, rigidity & spindle RPM
In PEB design, Z-section purlins are preferred over C-section because:
A) They are heavier
B) They have better overlapping strength
C) They cost less
D) They reduce steel grade requirements
B) They have better overlapping strength
The spindle taper standard used in heavy-duty CNC drilling machines for PEB fabrication is usually:
A) HSK 32
B) BT 40
C) BT 50
D) CAT 30
C) BT 50
Which welding consumable is commonly used for Submerged Arc Welding (SAW) in PEB manufacturing?
A) E6013
B) Flux-cored wire
C) SAW Flux + Wire Combination
D) Tungsten electrode
A) E6013
B) Flux-cored wire
C) SAW Flux + Wire Combination
D) Tungsten electrode
C) SAW Flux + Wire Combination
Which factor affects chatter vibrations in CNC drilling the most?
A) Cutting speed only
B) Tool geometry, rigidity & spindle RPM
C) Coolant temperature
D) Operator experience
B) Tool geometry, rigidity & spindle RPM
"Kerf” in cutting means
Width of material removed by the cut
In CNC drilling, peck drilling cycle (G83) is used to
Break chips & clear them in deep hole drilling
In a typical gantry plasma table, how many primary motion axes are used?
(X-Y-Z)
Rule-of-thumb minimum bolt-hole diameter for good quality with high-def plasma is about:
1.2 × thickness
Overall Equipment Effectiveness (OEE) is:
Availability × Performance × Quality