What Does Ductility Mean?

November 19, 2014

The ability of a material to deform plastically without fracturing, is called ductility. In the materials usually machined in our shops, ductility is measured by determining the percent of elongation and the percent reduction of area on a specimen during a tensile test.


Ductility is often indicated by chip control issues in certain steels, as the chip readily deforms but does not separate from the work piece. This  can result in persistent burrs attached to the work .

Ductility arrives in our shops as indicated by burrs

Ductility arrives in our shops as indicated by burrs

Ductility can also mean  long stringy chips that can form a dreaded “birds nest” engulfing the tool and work piece.

Test text

Birds nest chips present a very real danger to operators. Ductility can hurt!

Long necklace chips are another sign of ductile materials in machining.

long continuous chips resulting from ductile material can be controlled to keep them away from work piece and tool

Long continuous chips resulting from ductile material can be controlled to keep them away from work piece and tool.

Short chips curled into  “sixes and nines” showing a bit of heat discoloration are typical of less ductile materials and dutile materials machined at proper parameters using chip breakers and high pressure coolant delivery.

Note the touch of heat discoloration shown on the chip as well.

Chips that look like sixes or nines showing a bit of heat discoloration are desired for safe practice.

 

In our machining practice we would prefer materials that are “crisp” rather than ductile.

In order to successfully deal with ductile materials, strategies such as chip control features on inserts, wiper style inserts, through tool coolant,  interrupted cuts, chip breakers, and high pressure coolant can be considered.

Dialing in the appropriate feeds, speeds and depth of cut are crucial too.

Birdsnest photo courtesy Garage Journal

All other photos by author.


Burr Removal On Machined Product- Vectron Deburring

February 29, 2012

Certain materials and design features are more prone to the creation of burrs, especially ductile materials, intersections of machined features, and sometimes threads.

Can you really afford to remove these by hand from 50,000 parts produced?

Burrs are unwanted raised material remaining on a machined part as a result of prior manufacturing operations.

Burr removal is important because burrs can:

  • Prevent proper assembly of components;
  • Create a safety hazard (Cuts) for employees handling the parts;
  • Interfere with or prevent proper functionality  of parts after assembly;
  • Contaminate systems when they break off after assembly and in use.

PMPA member Vectron Deburring uses thermal or electrochemical processes to assure burr removal.

Thermal deburring is a batch process involving very intense heat in very short durations. It’s like being inside an explosion.

Electrochemical deburring applies an electrical current to the areas where the burrs are located. The current carried by the electrolyte actually dissolves the burr material. This process can actually create a controlled radius on the workpiece by its action.

At 5:45 P.M. on February 7, a  PMPA member posted a question about how to to get rid of burrs on the threads of his 304 stainless parts on PMPA’s members only Quality Listserve.

By 8:00 A.M. on February 8th, he had received 4 responses from companies located in three states and one province in Canada- all naming Vectron Deburring as their preferred source.

The pictures we’ve included above show why.

Vectron Deburring deburrs.

PMPA Listserves- Quality, Manufacturing and Technical, Corporate, Human Resources and others- connect members with solutions to problems and tools they can use.

Vectron loves to deburr.

PMPA would love to connect you with the answers that you need to stay sustainable and successful.