1. Analysis of Drive System for Powder Compaction – A Flex
Body Application in MBD Simulation
Chandan Joardar
GM (R&D)
SciTech Centre
7 Prabhat Nagar
Jogeshwari – West
Mumbai – 400 102, India
Abbreviation: Dosator – An entity in a filling machine, delivering a measured amount of powder
inside a capsule.
Keywords : Dosator, Flex Body, MBD
Abstract
The cam and follower arrangement is the source of drive in the powder compaction sub-system of
the Dosator in the machine for filling powder in capsules. The required motion and force at the
Dosator comes out of the cam through the follower plate.
Any deformation in the cam and / or the follower plate causes corresponding loss of motion at the
Dosator end. For satisfactory operation of the Dosator, it is desired to be maintained with in 50
µ.We have identified the follower plate as the most potential candidate to affect this specification by
way of its deformation while in motion. Accordingly we have undertaken a Flex-body analysis in
MBD for this part.
On the basis of analysis of results, the design of the follower plate has been modified to keep the
maximum deflection below 50 µ and thereby maintaining the Dosator end deflection within 50 µ as
well.
Introduction
Dosator system is the most crucial part for a capsule filling machine. Deflections in a
component due to loads of other parts can cause loss in filling the formulation powder inside
capsule's body.
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2. Follower plate which is hinged at point A works as a cantilever, under the influence of the forces
coming through the 3 revolute joints, is liable to get deformed if not strong enough. It was observed
that a deflection of 1 mm can cause a loss of 10% of powder filling inside a capsule body.
Motion View/Motion Solve was used to perform MBD simulations and a flexible body was used to
observe the stress generated and deflections in the follower plate.
Figure 1: Dosator System
Objectives:
Following were the objectives of the current study
• To study the stresses and deformation generated in follower plate and then re-design an
optimum plate that satisfy the capsule filling specifications.
• To set up a model for the Dosator assembly , which can be used to test under different
specifications( varying rpm, compaction load etc)
• To compare the MBD simulation results with the actual machine
Process Methodology
The process flow mentioned in Figure 2 is used to perform this analysis. The detailed description of
each process is mentioned below.
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3. 1. Geometry in Motion View: Dosator system was extracted from CAD model of the complete
machine and then it was imported in Motion View. Various constraints and joints were applied in
order to make the model in compliance with the real machine.
2. Identify Potential Candidate: Once the model was assembled, the trend of forces and
motion flow was analyzed and it was identified that follower plate is the most likely to deform in
operation and cause loss of motion at the Dosator end that in turn can cause loss of filling in the
capsule. Accordingly, it was decided to perform flex-body analysis of this component and
strengthen it adequately to meet the performance specifications.
Geometry in Identify Potential
MotionView Candidate
Deflections Simulation Create Equivalent
Stresses &Forces Parameters Model
Test correlation Results
Figure 2: Process Chart
3. Create Equivalent Model: Dosator system was extracted from the main model and a point
mass body was used to model the component that apply load on the cam follower plate. Mass of the
point mass body was half the mass of the rest of the components as there are two follower plates to
share the load and Flex-body analysis was done on a single plate.
Figure 3: Equivalent Model
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4. 4. Simulation Parameters: Two major input parameters used for simulations are
• Velocity of the cam shaft – cycle time of 0.468 seconds was fixed that corresponds to desired
output of the machine
• Velocity of Dosator sub-system
Results & Discussion
Four important performance parameters considered for comparison with actual machine are as
follows:
1. Bending Forces on follower plate
2. Deformation
3. Stress, and
4. Strain
The results of simulations are as follows:
Force Vs Time (Per cycle) Deformation Plot
Strain Plot Stress Plot
Figure 4: Simulation Results
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5. Most significant force comes at the follower plate in vertical direction that can bend it. We can
change Geometry and /or material of the plate on the basis of forces being applied on it. With the
help of Stress, Strain and Deformation plots we have strengthen the local areas where strain is the
most. By making some changes in geometry of the model deformation of the plate was restricted to
100 µ for the worst case scenario (116 rpm). For the regular range of operation it will remain within
50 µ.
Challenges
1. Correct Identification of potential component to undertake the analysis.
2. Modeling the simulation so that it closely represents the actual working situation/boundary
conditions under which the mechanism is working.
Future Plan
In the future developments of machines incorporating Dosator system, we shall make an early flex-
body analysis in MBD. Once the 3D CAD model is prepared it can be simulated for different sets of
parameters. Hence actual machine can be designed in accordance with the desired specifications.
Conclusion
Making flex-body analysis using MBD is very useful in new developments. However, it requires
allocation of adequate time apart from other resources. But, if we don’t do this we might land up
making trouble shooting activities during validation of the machine and eventually spending more
time than what was allocated at the beginning of the project.
Acknowledgement
I would like to express my gratitude and sincere thanks to Mr. Devesh Rajan, Undergraduate
Student, IIT Kanpur, Project Trainee, SciTech Centre for his valuable inputs.
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