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200 Top Compression Machine Interview Questions with Answers in Pharmaceuticals

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Compression machines are widely used in the pharmaceutical industry for tablet production. During production, process parameters shall be checked at regular intervals to ensure product quality. So pharmaceutical companies hire a person who has good sound knowledge in this area. so by keeping this in mind, we have prepared Compression Machine Interview Questions with Answers for fresher as well as experienced candidates.

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Most common Compression Machine Interview Questions with Answers

Q. What is the compression Machine?
Ans: A compression machine is used to manufacture tablets by compressing the granules/powders in the solid dosage form.n

Q. What is the principle of a compression machine?
Ans: The compression of the upper and lower punch in a die hole is the primary working principle of the tablet compression machine, and hydraulic pressure is crucial. This pressure is passed via the static fluid without being diminished. Any externally supplied pressure is distributed evenly in all directions by static fluid. Additionally, it enables the force to be increased as necessary. Increased hydraulic pressure results in a stronger compressive force being applied to the tablet, making it harder.

Q. What are the different parts of the tablet compression machine?
Ans: The compression machine consists of the following parts:

Hopper>Feeder>Turret>cums (fill, weight, and ejection cam)>punches (upper and lower)> tablets scrapper>scarper blade>tail over die> chute

Q. What is the MOC (Material of construction) of a compression machine?
Ans: Contact parts: Made up of SS 316

Non-contact parts: Made up of SS 304

Q. How much is the capacity of the compression machine hopper?
Ans: The average capacity is 20L, it also varies from machine to machine makers.

Q. How many types of feeders are available for compression machines?
Ans: There are mainly two types of feeders available for the compression machine:

  • Gravity Feeder
  • Force Feeder

Q. What is meant by a single Rotatory compression machine?
Ans: as the name indicates, it is single in rotation, which means that the machine has only one side of the discharge chute, two main rollers,s, and two pre-compression rollers.

Q. What is meant by a double rotatory compression machine?
Ans: Double rotatory means, the machine has both side discharge chutes and compresses the tablets on both sides. The double rotatory machine has one discharge chute on RHS and another on LHS.

Q. What is the benefit of the Double rotatory machine over the single rotatory machine?
Ans: The production output of the tablets is more than that compared to the single rotary machine. It also reduced the time and cost of production.

Q. What is the metal detector?
Ans: A metal detector is used to detect or remove the metal pieces on tablets after their compression.

Q. How to do a metal detector challenge test?
Ans: It is mainly done before the start of the operation and followed by every two hours while passing one by one (SS, Fe, and Non-Fe). the challenge test is passed if all the metal detector is rejected.

Q. What is the de-duster?
Ans: De-duster is placed below the chute to separate the powder from the tablets by passing the tablets from bottom to outside through a spiral helix.

Q. What is meant by AWC?
Ans: AWC stands for auto weight control.

Q. What is the principle for auto weight control (AWC) in compression?
Ans: AWC works on compression force. at this point first set the machine on a lower fill weight against the given standard limit and observe the avg—compression force.

Similarly set the machine for a higher fill weight and observe the avg—compression force.

Now set the target fill weight and run the machine, acquiring the reference value of force at desired parameter. now feed the higher and lower compression force values that were previously noted.

Q. What is the tooling in the compression machine?
Ans: The die and punches combination on the compression machine is called tooling.

Q. What is the MOC for punches and dies?
Ans: OHNS= OIl hardened non-shrinking steel (Tungsten)

HCHC= High carbon, High chromium steel.

Q. How many types of tooling are in a compression machine?
Ans: There are mainly four types of tooling in the compression machine, B tooling, BB tooling, D Tooling, and DB Tooling.

Q. What is B.Tooling?
Ans: B. Tooling identical to BB type except for lower punch size that is 3×9/16 inch long.

D. Tooling punch diameter is 25.4 mm and the diameter of the die is 38.10 mm whereas B tooling punch diameter is 19.00 mm and the die diameter is 30.15 mm.

Q. What is the dwell time in the compression machine?
Ans: The amount of time it takes for the punches to stop moving vertically and penetrate the die to their maximum under the major compression rollers is known as the “dwell time in compression.” When the compression rollers achieve flat contact with the punch head, dwell time begins. You can calculate the tablet press dwell time by dividing the punch head flat dimension by the turret tangential velocity.

Q. What is the work of pre-compression rollers in compression machines?
Ans: Basically, these rollers apply a small amount of force on the upper and lower punches. The purpose of this procedure is to eliminate any air that might be present in the powder or die.

Q. What is the role of the main rollers in the compression machine?
Ans: Main rollers exert a pre-determined amount of force (final compression force) to form the tablet. at that time compression force is greater than the pre-compression force. so it becomes necessary that the rollers remain stable without vibration during the manufacturing process. it ensures the production of tablets with consistency in thickness and size.

Q. What are the different stages in a Compression Machine?
Ans: The tablet compression machine is divided into four different stages:

FillingThe formulation is overfilled at the compression station
MeteringOverfilling is removed
CompressionTablets formation by pressure exerted by punches within the die
EjectionTablets Ejection from dies

Q. What are in-process checks during compression?
Ans: The following parameters shall be checked before starting the batch and during running at a given time interval.

  • Physical appearance
  • Description of tablets
  • Avg. weight
  • Individual weight variation
  • Hardness
  • Thickness
  • Diameter
  • Friability test
  • Disintegration test (DT)

Q. What are the units of hardness in tablets?
Ans: The unit of hardness is Kilogram (Kg), Newton (N), Pound (lb), and Strong-cobb (SC).

Q. What is the friability test?
Ans: Friability is defined as the %age of weight loss in powder form from the tablet surface due to mechanical action. friability test is performed to measure weight loss during transportation.

Q. What is the formula for the friability test?

formula for the friability test

W1= Weight of tablets before Friability test
W2= Weight of tablets after Friability test

Q. What is the friability limit?
Ans: The Friability limit for tablets should not be more than 1.0%.

Q. How many quantities of tablets are required for the friability test?
Ans: If the tablet’s individual weight is equal to or less than 650 mg. then take the sample of the whole corresponding to as near as 6.5 gm equivalent and if tablets with individual weights are more than 650 mg then take a sample of 10 whole tablets to perform a friability test.

Q. What steps are to be taken before calculating the friability test?
Ans: Tablets must be de-dusted prior to and after use.

Q. What are the tablet’s defects during processing?
Ans: The following defects may be encountered in tablets during compression:

  • Mottling
  • Lamination
  • Picking
  • Double impression
  • Sticking
  • Capping
  • Weight variation

Q. What is mottling?
Ans: Mottling is the migration of color within tablets

Q. What is Lamination?
Ans: Lamination is the separation of the tablets into two or more layers after compression.

Q. What is the Picking in tablets?
Ans: Picking is the powder adhesion at the tip of the punch, this may result in missing the powders from the tablet surface.

Q. What is the double impression?
Ans: It is the formation of the grove on the lower side of tablets. Double impressions are generally seen in tablets where a hologram is needed.

Q. What is the sticking in tablets?
Ans: Sticking is the adhesion of tablets’ localized portion to the punch faces resulting in quality loss.

Q. What is capping?
Ans: Capping is the partial and complete separation of the tablet’s top or bottom crowns.

Q. What are the weight variations in the tablets?
Ans: Weight variation is the change in the individual tablets’ weight, this may be because of the powder flow properties or may be due to the wrong tooling setting.

Q. Tell me the common Tablet defects due to other factors.
Ans: Black spot/oil spot/foreign particle and embossing/debossing.

Q. What is the weight variation limit for tablets?

Avg. wt. in mg (IP/BP)Avg. wt. in mg (USP)%Deviation
80 mg or less130 mg or less ± 10%
more than 80 mg or less than 250 mg130 mg to 324 mg ± 7.5%
250 mg or moreMore than 324 mg ± 7.5%

Q. What is the uniformity of mass variation?
Ans: As per the IP/BP/Ph./Eur. the limit for uniformity of mass

Avg mass in mg% Deviation
Less than 300 mg ± 10%
300 mg or more ± 7.5%

Q. What is zero position in a Compression machine?
Ans: Machine without force or pressure applied on rollers.

Q. What is a Load cell?
Ans: A load cell is a force transducer. it converts a force such as tension, compression, pressure, or torque into an electrical signal that can be measured and standardized.

Q. What is an encoder?
Ans: An encoder is a device or process that converts data from one former to another. in position sensing, an encoder is a device that can detect and convert the mechanical motion to an analog or digitally coded output signal.

Q. What is load cell calibration?
Ans: For load cell calibration dummy punches and dies are installed at a particular position in the compression machine and the external encoder is attached to the machine encoder after applying pressure on the PLC of the machine the external encoder should be matched.

Some Technical Compression Machine Interview Questions

Q. Why station in a compression machine always come with Odd Numbers?
Ans: Odd numbers are generally called 23, 29, and 49, etc. Compression machines always come with Odd Numbers because of to maintain the dynamics balance.

Q. What types of food-grade oil are used in pharmaceutical machines?
Ans: Polyalphaolefin oil is generally used as a Food-grade oil in pharmaceutical machinery.

Q. Why Polyalphaolefin oil is best as a food-grade oil?
Ans: Because of its high viscosity and can be sustained at high temperatures.

Q. Tell the ISO certification used for food-grade oil.
Ans: The food-grade oil shall be certified by ISO 21469, and the supplier must be registered with the National Sanitation Foundation.

Q. Which CFR section or parts apply for lubricant usage with % permitted?
Ans: 21 CFR part 175 section 178:3570

Q. Tell me the types of food-grade oil used in pharmaceuticals.
Ans: The main types are as follows:

  • H1 Grade lubricants
  • H2 Grade lubricants
  • H3 Grade lubricants

Q. What are H1, H2, and H3 Grade oil?
Ans: H1 grade lubricants: This type of oil/grease is used for the machine where the chances of context with the product are high.

H2 Grade lubricants: These types of oil/grease are used to lubricate the parts of the machine that do not have a chance of contact with the drug product.

H3 Grade lubricants: These types of oil are used for transportation equipment like trolleys or stackers.

Q. Which types of tablets are exempted from DT testing?
Ans: Chewable tablets

Note: More informative on Compression Machine Interview Questions will be added on a regular basis, so visit this page daily for updates.

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