Burr and Deburr

Burr and deburr
Burr and deburr

We probably all heard about this old saying in our lives: “To err is human, to forgive divine.” Of course we are not going to talk about making mistakes and forgiving people here. It is that the saying perfectly matches the topic we are about to discuss this time: burr and deburr. A burr refers to a small piece of material left on the part after processing. No matter what manufacturing method we are using, burrs sometimes are inevitable. Take die casting parts for example, burrs are likely to form on the shut-off surface. Besides, drilling can also result in burrs around the hole.


Why we have to remove the burr?

Even though it is small, a burr can possibly result in functionality problem of a workpiece, assembly failure, and even injury of assembly operators or customers. Especially for some parts the surface is extremely critical, burrs will not be allowed. In that way, deburring process will be necessary. Therefore, how to remove the burrs without harming the functionality of the parts then reflects the techniques of a manufacturer.


Generally, there are 5 kinds of different deburring methods: manual, electrochemical, thermal energy, cryogenic, and mechanical. Among these 5 methods, manual deburring is most common process as it is more cost-effective. Here, APPORO has a case study on manually deburring the die casting parts.


Case study on deburring the die casting parts

There is a zinc die casting project that APPORO has been cooperating with one customer on for several years. According to the drawing of this item, there is a hole with slope end on the shut-off surface. So, this design increases the possibility of having burrs on its edge. Because APPORO already noticed that situation, when we moved to the mass production process, we always examined every part carefully and removed the burrs on it. The customer has always been content with the quality all this time.


To remove the burrs by chamfering
Burrs were aroound the end of the hole


However, recently the customer placed an order of these zinc die casting parts again. After the die casting process, we used tumbling to remove the burrs, and then reamed the parts so the dimensions could be within the tolerance. However, when we were inspecting the parts, we found out that the parts were still with burrs. Because the burrs were around the hole end, we knew the root cause was that the reamer had already worn down. As a result, we changed the reamer instantly and deburr the parts again by chamfering. The situation was thus well solved. Of course, there was no influence on the quality of these zinc die casting parts. And, eventually, our customer was satisfied with them. APPORO pays attention to every trivial detail, so we can always offer the best quality to our customers.


Are you looking for a reliable manufacturer that can help produce your parts without burrs? No matter what needs you have, APPORO will strive to meet your expectations. Contact APPORO for a free project review and get a RFQ today!


If you haven’t had the drawing for your project, you can also learn more about: How to Make Your Own CAD Drawing?

Aluminum Anodize Coating Failure

Aluminum anodizing is to produce oxide layer on the surface of aluminum parts to improve the capability of anti-corrosion. Actually, we had talked about this topic in previous case study. But, in this topic, we are talking about aluminum anodize coating failure. The failures caused by various issues on a aluminum CNC machining part generally fall into some of the following categories:

1.) exposure to chlorine based solution

Chlorine is very reactive and causes pitting corrosion by removing the oxide layer. Be careful if Chloride ion in a sulfuric acid electrolyte exceeding a critical level of chloride of 80 ppm. Please also notice that chlorine based solvents are for degreasing which may also cause acid pitting.

2.) exposure to very acid or alkaline solution

Solutions, pH lower than 4 or higher than 9, has the ability to break down the oxide layer and make the underlying aluminum susceptible to corrosion. Generally speaking, to rinse completely the aluminum anodize part is the most satisfactory method of eliminating this problem.

Blind holes v.s. anodizing failure

The anodizing failure rate can be high if your CNC aluminum parts featured with blind holes. If the high acidity anodization solution are not well removed from the blind holes, the liquid will flow out and damage the surface of CNC aluminum parts resulted in flaking-off and spots on its anodiizing surface.


Below photo showed an aluminum CNC milled part etched by acid residues. The white, dirty, flaking off oxide powder surrounding the threaded hole is gradually getting worse if no further action against it.

Aluminum anodize can be failure on occasion.
Aluminum anodize failure because of acid.


Preventive action to against failure of aluminum anodize

As described above, to rinse and clean the blind hole on a CNC aluminum anodize part is the best way to remove acid solution. It is a MUST to take this preventive action to against failure of anodizing.


Should you have any questions about aluminum anodize or other RFQ, feel free to send us RFQ for project reviewing.

Inner Thread Machining by Using Fluteless Tap

There are many ways for thread drilling in metalworking. As for external thread, both thread rolling and thread dies are most common used. As for inner thread machining, we generally use taper/second/bottoming three steps thread tapping or fluteless tapping.

Frankly speaking,  to drill a deep and small inner thread on high hardness or malleability raw material is a difficult mission. Thread machining is all about factors. Such as hole diameter, the forming speed and types of drill bet on the responses: torque, hardness, feeding rate, and thrust force of the form tapping process. Fluteless tap is the one of the best tooling for machining inner thread on CNC turning machines.

Fluteless tap thread machining
Thread machined by using fluteless tap


What is the Advantages of Fluteless Tap?

Fluteless tapping, so called form tapping. The screw thread is formed by plastic deformation of a working metal under high level of torque. And, well monitored operation processing to avoid tool bit breakage when thread machining.

Fluteless tapping can form a perfect screw thread with no waste material in a pre-drilled hole. Besides, it is kind of opposite style of external thread rolling method. The inner screw thread machined by fluteless tap is with higher strength and less error of pitch diameter. So, we mainly use fluteless tap machining inner thread on aluminum part, brass part and zinc part when in CNC precision manufacturing.


Thread Machining in Industrial Application

Let’s consider automobile industrial application as an example. Mechanical components need to have threaded parts allowing quick and precise assemblies and dis-assemblies. The engine heads manufactured with non-ferrous metals have a excellent capacity to deform and maintain an acceptable mechanical strength. As a result, thread formed by fluteless tapping can guarantee perfect full threading and high tensile strength.


Inner thread formed via fluteless tapping
Zoom in on the inner thread of cut part


However, inner thread machined by fluteless taps have some peculiarities. For example, the appearance of a split crest on the top of the thread. Above phenomenon is directly rely on the initial pre-drill hole diameter. In addition, the smaller the inner diameters, the slighter the split crest on the top of the screw thread after flutless tap forming.


the appearance of a split crest on the top of the thread
Split crest on the thread


Feel free to ask us if any questions about fluteless tap on CNC precision machining parts. Pls send us your RFQ for free project reviewing.