IC 349 MU Project Report

IPD 04 – 3D Printer Post Curing Apparatus(WIE)




Hong Kong Polytechnic University

IPD 04



IC 349

IPD 04 – 3D Printer Post Curing Apparatus

Final Report








Law Tsz Ying


Chou Chun Wai


So Pak Man


Cheng Cheuk Hang


Chung Tsz Kwan


Leung Hin Tong


Ko Ching Yi






Procedures for taking the models out

User Requirement and Analysis

Research before Design

-The effectiveness of the reinforcement solutions

- Information of wax

Design Mind Map


Suggested Design

-Spray Approach

-Dipping Approach

Design Phase

-Conceptual design

-Final design

-Material selection

-Safety issue

-BOM (bill of material)

Project Management

-Manufacturing work flow



Manufacturing part



       -cutting machine


       -Hardware of the control






Working Procedure of the program

Guild line for user

Problem and solution






Rapid Prototyping (RP) is a group of techniques used to quickly make a scale model with the aid of CAD drawing. In RP, 3D printing technology is usually applied in the construction of the model.


3D printing is a process to make a three dimensional solid objects from a digital model by using additive processes, where an object is created by laying down successive layers of material. The process is quick and convenient to give out a scale model which is useful to be a prototype of a product or for the medical use, for example, the investigation of a patient’s skull to find out the symptom of the patient.


Our project is WIE-based, in which we corporate with Z Corporation( commonly abbreviated ZCorp). ZCorp is a company good at the development of 3D printers( Zprinters), in which their own ZCorp plaster powder is used as “ink” for the 3D printing process. Their Zprinters are now used all over the world( in the industrial centre of POLYU, there are four Zprinters working). These 3D printers, promote the convenience of 3D printing much.


The models of 3D printing can be made quickly and conveniently, these models, however, are quite weak and brittle. Without a post curing process for the reinforcement of these models, they will be broken easily. Therefore, a good post treatment is a must for these RP products. And, Our Project is to design a post curing apparatus for the reinforcement of these RP products. In this project, a post curing apparatus is manufactured.




I. To design an apparatus for the reinforcement of the brittle and weak RP models.


II. To enhance the quality of these models after treatment.


III. To minimize the labor intensive of the post curing stage and make it as convenient as possible.


IV. To make the whole process more time-saving.


Procedures for taking the models out


After the 3D printer printing out the models, there are some steps to take them out carefully from the machine. Here shows the procedures.




1.    Turn off the power supply and open the cover of the machine.


2.    Take a plastic card to separate the loose power and our model in order to take it out easily.


3.    To prevent the power spread everywhere, a vacuum cleaner is needed to clear up all loose power.


4.    After all loose power being removed, the model can take out easily and put it on the tray.

描述: C:\Users\PP\Desktop\MU04\2012-08-27 11.51.11.jpg


5.    Put all the models inside an air gun machine.


6.    Start the air gun to remove the remaining loose powers which still stick with the models especially in the detailed parts.


7.    Turn the model upside down and repeat the steps 6 again until all the loose powers have been removed.


8.    Take out the clean models.

User Requirement and Analysis


In the interaction with the users, we can find out different kind of problems about the post curing stage. To realize the needs of the users properly and correctly, we have to ruminate over what they said, and summarize all of their views and needs, and finally find out what they actually mean and want.



User Statement

Interpreted Needs

Time saving problem

Some users said it needs takes a few minutes to almost half an hour, or even more for the post curing process. Also during the process, the user who does the post curing process cannot do another thing, which lowers the efficiency of a workshop in a hustle.

It is better to have a more time-saving method. And also, a method for post curing process with higher automation will be appreciated.

The Smell Problem

In the post curing process, a user coats a thin layer of glue to reinforce the structure of the model. The users said that the glue may give out some disgusting smell which makes the process unpleasant.

It is better to have a method to make the process with a less unpleasant smell treatment or odorless or even make the process in a high ventilation environment.


The above table of the user needs identification shows what we have found about the users’ opinion and what we think the real message the users want to convey to us. After knowing the real thought and the desire of the users, we generated our design concept based on their needs.

Research before Design


1. The effectiveness of the reinforcement solutions

Before generating the design concept of the apparatus, we first find out the effectiveness of reinforcement of the solution on the model. First, several models were added into different solutions, after dipping, the time need to dry the models were marked. After drying, the models are taken to the impact test to see if they are strong enough. The table clearly shows the time needed to dry and also how much force the strengthened models can withstand.


Dry time



Salt water

90 mins


Difficult to dry

White wax1

60 mins

Not broken

Pre heat

White wax2

60 mins

Not broken

Pre heat

Red wax

60 mins

Not broken

Pre heat

Hair gel

30 mins



No solution added1




No solution added2




AA glue

20 mins


Heat distribute

Latex paint

40 mins



Nail polish

30 mins


Smelly, expensive

Sugar water

90 mins


Difficult to dry


120 mins


Very difficult to dry






Salt water



More white





More hard






2. Information of wax

Here is the rough information about melting point of different types of wax, this information allows us to distinguish which type of wax is better for the reinforcement process.


Type of Wax

Melting point ()

Paraffin Wax


Container Wax


Mould Wax

60 - 62

Dipping Wax



Generally, the melting point of wax lies on around 60 . And Wax does not melt immediately on heating but passes through several intermediate states :

Solid → Plastic → Semi-plastic → Semi-liquid →Liquid

Design Mind Map


The design mind map is based on the users’ needs and desire. Also, we think of the mechanism roughly and simply based on two main kinds of reinforcement method.

This mind map helps us to clarify the problems clearly.


In this mind map, the post curing method is divided into two main session: the dipping approach and spray approach. And we think of what components need to be fulfilled to achieve these two approaches.


For dipping into wax solution, we consider the up and down movement mainly, to achieve this movement, a control system may be involved for automation. Also, to make the wax in the molten state, heater is needed.


For spraying approach, we need to think of how to spray all surface of the model, rotation may be needed to do so.


We also write down some design specification on this mind map, such as the size, users’ needs, and other precaution of using, to make sure our design is all-rounded.


In summary, this mind map provides a clear design brief and elements to our design, making our design and manufacturing process smoother.



The design mind map shows what else criteria should be included on our design, while in the brainstorming stage we think of the features of the machine, for example, how to hold the model, how the movement, mechanism works, etc.

This tetrahedron shape can hold the model with its three edges. As the figures shows, different size of model can also fit into the tetrahedron shape.


The below hexagonal ring applies the similar mechanism to hold the model.


This plates has many holes on it, when the model is placed on it, and then it is dipped into the solution, the solution can coat the surface of the model through the hole.


In this method, the model is held by the small pins (the pins are packed tightly), and taking out the model, the pins go back to its original position


Suggested Design


1. Spray Approach


In the spray approach, a salt solution is used for the reinforcement solution.

As the figure shows, the RP model is held by using the pin, so that the model can be suspended and its bottom can also be sprayed with salt water. Besides, there are several nozzles to give out salt solution, in front of the model and below it will be the fixed nozzles, whereas the top nozzles can be move along x and y axis, which is similar to the 3D printer mechanism. For a thorough coating of salt water, the holding platform is also rotating.

2. Dipping Approach