Proses mencanai

Mesin pencanai meja

(1) Pengenalan  
  
      Proses mencantikkan atau meratakan sesuatu permukaan dengan menggunakan mesin pencanai dengan cara mengenakan permukaan bahan kerja kepada roda pencanai yang sedang berpusing sehingga menghauskan permukaan itu dinamakan proses mencanai.

Bentuk roda pencanai telah ditentukan oleh  Persatuan Pembuat Roda Pencanai. Ia terdapat berbagai bentuk , dan yang lazimnya digunakan dalam bengkel kejuruteraan. http://en.wikipedia.org/wiki/File:Rotating_grinder.gif

(2)Bentuk roda pencanai

    Dalam bengkel kejuruteraan terdapat berbagai bentuk roda pencanai yang digunakan untuk kerja mencanai. Lihat rajah A , bentuk  ( a ) hingga ( h ) digunakan sebagai roda pencanai piring yang digunakan pada mesin pencanai selinder , mesin pencanai permukaan dan kerja kerja am. Manakala roda bentuk cawan iaitu bentuk ( j ) hingga ( l ) digunakan pada mesin pencanai permukaan. Bentuk ( m ) , ( n ) dan ( p ) digunakan pada mesin pencanai mata alat pemotong dan bentuk ( r ) untuk kerja mencanai alur dan mengerat ( Lihat Rajah A ).



Rajah A

  

     3.  Komponen Asas Roda Pencanai. ( Lihat Rajah B ).

      Roda pencanai mempunyai dua komponen asas iaitu :

i.              Pelelas.

ii.            Pengikat.

          i.  Pelelas

          Pelelas diperbuat dari bahan yang sanggat keras dan dapat memotong atau lelas bahan yang lain. Apabila pelelas digunakan sebagai pencanai, ia dapat meratakan permukaan yang kasar serta melicinkan garis garis atau calar calar yang terdapat pada permukaan.

          Pelelas dibahagikan kepada dua jenis iaitu :  

a.    Pelelas asli.

b.    Pelelas tiruan.  

         Pelelas asli adalah bahan semula jadi yang terdapat dibumi. Pelelas ini tidak sekuat pelelas tiruan. Antara pelelas asli yang biasa digunakan ialah :

i.              Pumica.

ii.            Batu pasir.

iii.           Amril.

iv.           Rotten stone.

v.            Intan.

Pelelas tieuan adalah buatan manusia dan dibuat direlau letrik dan lebih keras daripada pelelas asli. Pelelas tiruan yang biasa digunakan ialah :

i.              Silikon karbide.

ii.            Aluminium oksida.

iii.           Intan tiruan.

iv.           Zircona – aluminium oksida.

v.            Doron karbida.

         ii.  Pengikat

         Bahan pengikat adalah menentukan kekuatan roda pencanai , samada roda jenis roda tegap atau roda mudah lentur. Pengikat juga menentukan jumlah daya yang dikhendaki untuk mengeluarkan satu zarah pelelas dari roda. Ini sanggat penting menentukan kesan pemotongan. Terdapat lima jenis pengikat yang biasa digunakan iaitu :

                        i.         Kekaca .

                        ii.         Silikat.

                        iii.       Syelek.

                        iV       .Getah.

                         v.       Damar.





Rajah B. Komponen asas roda pencanai

Kemahiran diri

Burung peguin

Definasi kemahiran ( skills )
Kebolehan melakukan,mengendalikan,mengoperasikan dan sebagainya yang berkaitan dengan kemampuan pergerakkan tangan ataupun anggota badan yang lain ialah salah satu definasi kemahiran.Semua manusia mempunyai kemahiran tersendiri tidak bergantung kepada tahap akademinya.

Definasi kemahiran mengikut wikipedia
A skill is the learned capacity to carry out pre-determined results often with the minimum outlay of time, energy, or both. Skills can often be divided into domain-general and domain-specific skills. For example, in the domain of work, some general skills would include time management, teamwork and leadership, self motivation and others, whereas domain-specific skills would be useful only for a certain job. Skill usually requires certain environmental stimuli and situations to assess the level of skill being shown and used.
People need a broad range of skills in order to contribute to a modern economy and take their place in the technological society of the twenty-first century. An ASTD study showed that through technology, the workplace is changing, and so are the skills that employees must have to be able to change with it. The study identified 16 basic skills (Carnevale, 1990)^{[citation needed]} that the workplace of the future would need in the employee of the future.

Foundation skills
From the employer's perspective, the skill of knowing how to learn is cost-effective because it can mitigate the cost of retraining efforts. When workers use efficient learning strategies, they absorb and apply training more quickly, saving their employers money and time. When properly prepared, employees can use learning-to-learn techniques to distinguish between essential and nonessential information, discern patterns in information, and pinpoint the actions necessary to improve job performance. Many employers - particularly those dealing with rapid technological change see the learning-to-learn skill as an urgent necessity. Productivity, innovation, and competitiveness all depend on developing the workers' learning capability. Machinery and processes are transferable between companies and countries, but it is the application of human knowledge to technology and systems that provides the competitive edge.

Basic skills competence
The inability of large numbers of new workers to meet reading, writing, or computational (simple mathematics) standards is an economic and competitive issue. This forces employers to spend more on these critical competence skills. The majority of workers are literate and numerate but frequently, cannot use these skills effectively because they are rusty when called upon to use mathematical principles they have not used for 20 years, because they must use the skills in a context different from the one in which they originally learned them, or because they do not understand how to expand or apply the skill.

Communication skills
Formal education in communication has been directed at reading and writing skills that are used least in the workplace. Most have only one or two years in speech related courses and no formal training in listening. Workers who can express their ideas orally and who understands verbal instructions make fewer mistakes, adjust more easily to change, and more readily absorb new ideas than those who do not. Thus career development is enhanced by training in oral communication and listening because these skills contribute to an employee's success in all of the following areas: interviewing, making presentations at or conducting meetings; negotiating and resolving conflict; selling; leading; being assertive; teaching or coaching others; working in a team; giving supervisors feedback about conversations with customers; and retraining. Employees spend most of the day communicating, and the time they spend will increase as robots, computers, and other machines take over mundane, repetitive jobs