Compounding Process - Seeking Generic Process Flow Diagram for Compounding Process

[davis007]

I have just started as a Manufacturing Quality Engineer after 8 years in Product development R&D and am a little lost in all the acronyms, methods, tools, etc. After reading information in several places it seems that the place to start is to generate a flow diagram of the process. (No my company does not currently have one.)

Can anyone point me to a general flow diagram for a compounding process? I realize that this would need to be tailored to my situation but was hoping for a starting point.

A more general question is do you know of a step-by-step set of instructions for developing and implementing a QMS at a company that does not have one currently?

Thanks for any help.

 

[Miner]

While this is not all-inclusive, there are some basic steps that you will need to take first.

1. Establish the structure of your documentation system. Questions to ask yourself are: Will it be policy, then procedure, then instruction or another format? How will you number the documents? Will it follow the sections in the ISO standard or your business processes?
2. Establish a standard format and required content for the documents.
3. Establish the document control system to immediately control the documents that will be generated.
4. Establish the record retention system to retain the records generated by the documents and the training.
5. Establish the training system to train personnel in the new documents.
6. Establish the Management Review system to track progress of the implementation.

After these initial steps, the sequence for the rest of the system is less critical.

 

[Douglas E. Purdy]

Starting from scratch?

Can anyone point me to a general flow diagram for a compounding process? I realize that this would need to be tailored to my situation but was hoping for a starting point.

A more general question is do you know of a step-by-step set of instructions for developing and implementing a QMS at a company that does not have one currently?

Thanks for any help.

I think that you have it right. Start with understanding a process and then manage that process by developing a continual improvement process. From there you can develop your system by standardizing the structural aspects of the system to ensure uniform understanding of the business processes and how to continually improve them.

As for a general flow of a compounding process, I have no idea what you mean. But you might want to start with generating a turtle (identifying the scope, the inputs and outputs, etc. - see attachments). From there you should be more capable of flowing the process. There are plenty of examples of flows on The Cove, and they come in different varieties.

Doug

 

[davis007]

Thanks to you both for the help and advice. I am still trying to get my mind around what type of process flow chart is most usefull, as there seems to be more than one to choose. The turtle form looks very helpful to start organizing the scope of the process.

Again thanks for the help.

Ed

 

[davis007]

Sorry I also meant to clarigy "componding process" in the plastics industry often plastics are modified with adjucts such as color, filler or other plastics. The process of mixing these materials and forming new pellets (plastics generaly come in small bead called pellets) is typically refered to as a compounding process.

Ed

 

[Miner]

You are correct that there are several formats for process flows. The type that you select should be based on what you need. You can start with a high level flow called a SIPOC. This is a simple 5-column spreadsheet listing Supplier, Input, Process step, Output and Customer for each macro-process step. You can use this to identify critical process steps, then do a detailed drill-down which list the input variables (contol, critical, SOP, noise, etc.) and output variables. The Turtle format looks good also, but the selection should be based on your need.

Regarding the compounding process flow, I have prior experience in rubber compounding both as supplier and as customer, and have found that this would only benefit you at the macro-level. Once you get into the details, there are significant difference between facilities.

 

[davis007]

Thanks for the info. I think, being new to this, I am confusing PROCESS diagrams with material flow diagrams and/or work procedures. Also, I am still strugling with the correct level of detail that I need to map the system. Perhaps more detail of what I am trying to achomplish would help the forum members help me.

We manufacture plastic parts using an injection molding process and a proprietary blend of polypropylene and additives. We manufacture the blend in house using a twin screw compounder. At times we have defects of various types in the parts. These defects are blamed by production on "variations" in the compounded material. At this time only one characteristic of the compound is measured, the loading of one of the several additives used.

I have been asked to:

1. Identify what about the compound is causing the injection molding problems.
2. Identify the key quality characteristic of the compound that will predict injection molding issues.
3. Identify testing methods for the key quality characteristics identified.
4. Identify curent and improved control methods for the quality characteristics identified.
5. Document the process for achieving 1-4 and loop through as a continuous improvement process.

What I am looking for from a diagram is two things.
1. Something to show managment that i can use to explain the system, process and controls.
2. A starting point for a logical approach to achiving my goals above.
3. A pictorial representation of the process to spure ideas for improvements.
4. A seperate diagram to document the process of continual improvement.

If any one has suggestions of how to attack this please let me know.

Thanks

 

[Miner]

What you are describing is an ideal Six Sigma project. I recommend that you develop a micro-level process flow that covers both the compounding AND the injection molding. Do not assume that the cause is from the compounding. Injection molding can also cause many defects. Both processes are suspect.

There are several tools to help you narrow focus to the higher risk operational steps such as a Cause/Effect Matrix followed by a Process FMEA. The next step is to identify all of the inputs to each step and label them as a controllable factor, noise factor (difficult or expensive to control), an SOP (Standard Operating Procedure). Then identify the process outputs from that step. This should meet your first three requirements.

The Six Sigma DMAIC (Define, Measure, Analyze, Improve, Control) process would address the fourth.

From prior experience in rubber compounding and injection molding, you will probably need to use designed experiments (DOE) to solve your problem. Both processes tend to have interactions that will foil one-at-a-time experiments. Before you start DOE's you will also need to validate your measurement systems.

On a final note: there have been many experiments run on the injection molding process that are available on the Internet. A little searching may help you better understand the process and what interactions to investigate.

 

[davis007]

Miner:

Thanks for the input. I do not mean to be dense but when you say a "micro-level process flow" are your refering to a process flow that includes all the inputs to individual unit operations, power supply, cooling air, steam, etc., as well as higher level inputs such as trainning, documentation, etc? It seems that the diagram would get overwelming very quickly with both sets of details. I hope what you mean is to include only the inputs and flow for the items needed by each unit op, power, heat, etc.

Thanks
Ed

 

[Miner]

A macro-level process flow might be Op 1: Compound, Op 2:Injection Mold.

A micro-level process flow for compounding might be Op 1: Weigh ingredient A Op 2: Weigh ingredient B Op 3: Mix ingredients A & B.

Inputs to the micro-level Op 1 might be: moisture content, % regrind; for Op 3: mix speed, mix time. For an injection molding example, it might be injection speed, pressure, preheat time/temperature. etc.

Outputs from Op 1 might be weight; Op 3 might be viscosity, etc.

The level of detail should be enough to give you outputs that you can measure and inputs that you can manipulate.

Hope this helps.