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Six Sigma blasting: A team approach

In the past, mine management would give an engineer or supervisor the task of production control and research, in an attempt to develop a process control system. For example, if blasting costs were a problem the engineer was given the responsibility for taking measurements and determining the reasons for the high cost. The responsibility for research was normally given to a technical person. However, once the causes had been identified, the upper management may or may not have implemented the engineer’s recommendations, because of a lack of understanding of the total problem. In addition, the drillers and blasters, who were not directly involved in the process, may simply have been given orders to be more accurate in their drilling. There was normally no direct control of the drillers. In other words, the recommendations were not enforced and further evaluations were not conducted to ensure drilling was corrected over the long term.

What this commonly used method lacks is the team approach and consistent monitoring and detailed reporting. For this reason, the older methods commonly fail in the long term. It has been the author’s experience that even when problems were identified and immediate changes made to correct them, these changes disappeared in a matter of months or years and the operation ended up being just as inefficient as before the system was implemented. This is often because of changes in management, changes in drillers/blasters, supervisors etc, and no follow-up or control on the process. The Six Sigma blasting program focuses on a team comprising all levels, from upper management to the driller and the shotfirer, to ensure co-operation and effective completion and control of the process, along with consistent monitoring and reliable, timely reporting.

Six Sigma is a manufacturing term used to describe a specific continuous improvement process. The process involves system inputs and outputs, determination of customer needs and the development of ways to ensure all outputs of the system are similar while utilising a team approach.

In Six Sigma processes, two main statistics are used to determine the success of the system: the system mean and the system standard deviation.


Precision Blasting Services has studied the process of drilling and blasting to identify variables that can be systemised to ensure a constant blasting operation. For its Six Sigma blasting program the company has found ways to correct the most common problems that quarries and mines encounter when drilling and blasting, including drill angles, drill hole drift, geologic variation and other factors.

The Six Sigma DMAIC methodology works well as a roadmap for Six Sigma blasting (see Figure 1). This methodology starts by defining the requirements and goals, as well as key milestones, project leads and project deliverables. The next step is the measure phase, which involves collecting the data needed to determine current blasting program opportunities. These can be either problems that are occurring or areas that can be improved upon for better results. The next phase is analyse, which takes a deeper look at the measurables collected and determines the opportunity areas that exist in a blasting program. The next step is the improvement phase, which develops potential solutions and assigns the failure measures for the program. At the end of this phase, the changes are incorporated into a blasting program and mark the start of the control phase. In this phase the standards for the new system are developed to ensure system failure does not occur and to determine the true process stability.

In the drilling and blasting sector, a great deal of time is spent considering the efficiency of drills, new products and better explosives. What is rarely considered is the system control aspect. In one case, a mine saved $US100,000 per year through product optimisation. When this same mine developed a Six Sigma blasting program, it saved more than $US400,000 per year. Below is the way Precision Blasting Services administers this process.

Six Sigma Team
Sponsor Leader







Define phase

During the define phase, one of the most important steps is to identify the true outcomes and requirements of the program. This could be a more uniform fragmentation size, a reduction in drilling and blasting costs, a reduction in vibration levels or more tonnes per shot.

The next important part of the design phase is to appoint a team that will implement the Six Sigma blasting process. The general team should be made up of managers, engineers, engineering technicians and the drillers and shotfirers. This ensures co-operation at all levels and begins the discussion on blasting system control.

After a team has been formed, jobs need to be defined for each member (see Figure 2). There should be a sponsor (the executive who will be sponsoring the program), the leader (the person responsible for implementing and guiding the team), a black belt member (normally an expert in drilling and blasting that will be identifying opportunities and solutions), green belt members (the people gathering data, helping with analysis and suggesting solutions) and team members (those assisting the team and helping implement the solutions). This team will meet on a scheduled basis (bi-weekly, monthly, quarterly, etc) and smaller groups inside this team will meet on a more frequent basis.

The next step is to develop a process map at the operation, to ensure everyone understands the process in place, areas for development and the end goals of the program.

Drill Angles Fragmentation sizing (WipWare system)
Drill depths Pull depth
Relief hole depth Drilling and blasting costs
Relief hole angles Vibration levels
Undercut depths Wall control and overbreak
Burden and spacing Floor control
Delay timing of holes  
Initiator accuracy  
Table 1. Key inputs and main outputs for definition and measurement. 

Measure phase

In the measure phase, the black belt and green belts will begin to take measurements throughout the blasting program. These should include both the inputs and outputs. In a complex blasting program, it can be difficult and time-consuming to measure all the different variables. This makes it important to know the end goal and ensure the black belt has a deep understanding of drilling and blasting.

A few key inputs and main outputs will be defined and measured. Table 1 (above) outlines some important first step areas.

This step also marks the beginning of the collection of baseline data that will measure the program’s success. It will generally take from one to three months to ensure a good, consistent baseline is collected and accurate inputs are matched.

Once the exact inputs and outputs have been designated, the monitoring of these continues and a more defined measure phase begins. To prevent overwhelming anyone who is collecting data, generally only a few inputs and outputs are measured over the long term. This also ensures the relationship can be tracked more accurately.

For example, considering fragmentation size (using the WipWare size distribution analysis, Figures 3 and 4) as the main output objective and burden, and spacing and drill depths as the main inputs, these can be tracked and analysed to form a relationship for future models.


Analyse phase

The analyse phase will be ongoing and concurrent with the measure phase and will take results from the measure phase and begin to construct the relationships and models. Some helpful tools in this phase will include using and updating process flows and maps, histograms, Pareto charts, scatter plots and other statistical analysis.

These tools can then be used to develop specific relationships between the inputs (x) and outputs (y). These can be fit to a Y=f(x) relationship that can be linear, logarithmic, exponential or one of a variety of other relationships. In a theoretical example, it was found that face advance in mining coal with undercut blasting methods was related with undercut depths by: Face Advance = Undercut Depth + 16cm

It was also found that the drill depth (especially drilling further than the undercut depth) had almost no effect on the face advance, and that this was an area for economic improvement through reducing the total drill depth and explosives used. The unnecessary drilling and explosive use were then considered economic losses per tonne (Figure 6).

After these relationships were developed, the next step was to determine why the undercut depths were not always at the designed level.


Improve phase

After achieving a consistent baseline (one to three months) from the measure phase and the development of relationships in the analyse phase, the improvement phase will begin. In this phase, model adjustments and specific designs will be constructed. In the previous example (face advance with undercut and drill depth) an employee was asked to take extra care to undercut a set 4.4m and drill shorter holes (4.2m horizontally). The process was then carefully examined, and the results were that the face advance still followed the previous equation; this reduced drilling by more than 8000m per month, along with the subsequent explosive cost associated with loading the additional 8000m.

After the design and testing phase, implementation of new systems and identification of scenarios that lead to failure of these systems will be conducted.

Control phase

The last phase of the Six Sigma blasting process is the control phase. Here, periodic monitoring of the inputs will be taken and graphed on quality control charts. This will ensure the systems created are meeting the designed goals. Standards and procedures will then be developed to ensure these processes are easily trainable and followed.

The next part of the control phase is to develop a total cost savings and transfer plan that can be given to the process owners. For example, if drill hole depth is a problem then at the end of the Six Sigma blasting process the drillers would begin taking their own depth readings and be periodically checked by supervisors or engineers.


After the transfer is complete, the project is officially finalised and closed. Following this step, the process can be reinitiated to consider other variables or the Six Sigma initiative can be terminated.

Six Sigma blasting is a new methodology for system control of the drilling and blasting process in quarries and mines. Using a DMAIC method to analyse and correct key inputs to achieve desired outputs, the Six Sigma blasting process has saved some sites more than $US400,000 a year by looking into areas that have not been traditionally considered.


Anthony Konya works for Precision Blasting Services (UK).

This article originally appeared in the March 2016 issue of Quarry Management (UK) and appears in Quarry with kind permission.

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